text: /**
   * @license Copyright (c) 2003-2022, CKSource Holding sp. z o.o. All rights reserved.
   * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
   */
  
  /* globals console */
  
  import Model from '../../src/model/model';
  import Batch from '../../src/model/batch';
  import Element from '../../src/model/element';
  import Text from '../../src/model/text';
  import Range from '../../src/model/range';
  import Position from '../../src/model/position';
  import LiveRange from '../../src/model/liverange';
  import DocumentSelection from '../../src/model/documentselection';
  import InsertOperation from '../../src/model/operation/insertoperation';
  import MoveOperation from '../../src/model/operation/moveoperation';
  import AttributeOperation from '../../src/model/operation/attributeoperation';
  import SplitOperation from '../../src/model/operation/splitoperation';
  import Collection from '@ckeditor/ckeditor5-utils/src/collection';
  import count from '@ckeditor/ckeditor5-utils/src/count';
  import { setData, getData } from '../../src/dev-utils/model';
  import { expectToThrowCKEditorError } from '@ckeditor/ckeditor5-utils/tests/_utils/utils';
  
  describe( 'DocumentSelection', () => {
  	let model, doc, root, selection, liveRange, range;
  
  	const fooStoreAttrKey = DocumentSelection._getStoreAttributeKey( 'foo' );
  	const abcStoreAttrKey = DocumentSelection._getStoreAttributeKey( 'abc' );
  
  	beforeEach( () => {
  		model = new Model();
  		doc = model.document;
  		root = doc.createRoot();
  		root._appendChild( [
  			new Element( 'p' ),
  			new Element( 'p' ),
  			new Element( 'p', [], new Text( 'foobar' ) ),
  			new Element( 'p' ),
  			new Element( 'p' ),
  			new Element( 'p' ),
  			new Element( 'p', [], new Text( 'foobar' ) )
  		] );
  		selection = doc.selection;
  		model.schema.register( 'p', { inheritAllFrom: '$block' } );
  
  		model.schema.register( 'widget', {
  			isObject: true
  		} );
  
  		liveRange = new LiveRange( new Position( root, [ 0 ] ), new Position( root, [ 1 ] ) );
  		range = new Range( new Position( root, [ 2 ] ), new Position( root, [ 2, 2 ] ) );
  	} );
  
  	afterEach( () => {
  		sinon.restore();
  		model.destroy();
  		liveRange.detach();
  	} );
  
  	describe( 'default range', () => {
  		it( 'should go to the first editable element', () => {
  			const ranges = Array.from( selection.getRanges() );
  
  			expect( ranges.length ).to.equal( 1 );
  			expect( selection.anchor.isEqual( new Position( root, [ 0, 0 ] ) ) ).to.be.true;
  			expect( selection.focus.isEqual( new Position( root, [ 0, 0 ] ) ) ).to.be.true;
  			expect( selection ).to.have.property( 'isBackward', false );
  		} );
  
  		it( 'should be set to the beginning of the doc if there is no editable element', () => {
  			model = new Model();
  			doc = model.document;
  			root = doc.createRoot();
  			root._insertChild( 0, new Text( 'foobar' ) );
  			selection = doc.selection;
  
  			const ranges = Array.from( selection.getRanges() );
  
  			expect( ranges.length ).to.equal( 1 );
  			expect( selection.anchor.isEqual( new Position( root, [ 0 ] ) ) ).to.be.true;
  			expect( selection.focus.isEqual( new Position( root, [ 0 ] ) ) ).to.be.true;
  			expect( selection ).to.have.property( 'isBackward', false );
  			expect( count( selection.getAttributes() ) ).to.equal( 0 );
  		} );
  
  		it( 'should skip element when you can not put selection', () => {
  			model = new Model();
  			doc = model.document;
  			root = doc.createRoot();
  			root._insertChild( 0, [
  				new Element( 'img' ),
  				new Element( 'p', [], new Text( 'foobar' ) )
  			] );
  			model.schema.register( 'img' );
  			model.schema.register( 'p', { inheritAllFrom: '$block' } );
  			selection = doc.selection;
  
  			const ranges = Array.from( selection.getRanges() );
  
  			expect( ranges.length ).to.equal( 1 );
  			expect( selection.anchor.isEqual( new Position( root, [ 1, 0 ] ) ) ).to.be.true;
  			expect( selection.focus.isEqual( new Position( root, [ 1, 0 ] ) ) ).to.be.true;
  			expect( selection ).to.have.property( 'isBackward', false );
  			expect( count( selection.getAttributes() ) ).to.equal( 0 );
  		} );
  	} );
  
  	describe( 'isCollapsed', () => {
  		it( 'should be true for the default range (in text position)', () => {
  			expect( selection.isCollapsed ).to.be.true;
  		} );
  
  		it( 'should be false for the default range (object selection) ', () => {
  			root._insertChild( 0, new Element( 'widget' ) );
  
  			expect( selection.isCollapsed ).to.be.false;
  		} );
  
  		it( 'should back off to the default algorithm if selection has ranges', () => {
  			selection._setTo( range );
  
  			expect( selection.isCollapsed ).to.be.false;
  		} );
  	} );
  
  	describe( 'anchor', () => {
  		it( 'should equal the default range\'s start (in text position)', () => {
  			const expectedPos = new Position( root, [ 0, 0 ] );
  
  			expect( selection.anchor.isEqual( expectedPos ) ).to.be.true;
  		} );
  
  		it( 'should equal the default range\'s start (object selection)', () => {
  			root._insertChild( 0, new Element( 'widget' ) );
  
  			const expectedPos = new Position( root, [ 0 ] );
  
  			expect( selection.anchor.isEqual( expectedPos ) ).to.be.true;
  		} );
  
  		it( 'should back off to the default algorithm if selection has ranges', () => {
  			selection._setTo( range );
  
  			expect( selection.anchor.isEqual( range.start ) ).to.be.true;
  		} );
  	} );
  
  	describe( 'focus', () => {
  		it( 'should equal the default range\'s end (in text position)', () => {
  			const expectedPos = new Position( root, [ 0, 0 ] );
  
  			expect( selection.focus.isEqual( expectedPos ) ).to.be.true;
  		} );
  
  		it( 'should equal the default range\'s end (object selection)', () => {
  			root._insertChild( 0, new Element( 'widget' ) );
  
  			const expectedPos = new Position( root, [ 1 ] );
  
  			expect( selection.focus.isEqual( expectedPos ) ).to.be.true;
  			expect( selection.focus.isEqual( selection.getFirstRange().end ) ).to.be.true;
  		} );
  
  		it( 'should back off to the default algorithm if selection has ranges', () => {
  			selection._setTo( range );
  
  			expect( selection.focus.isEqual( range.end ) ).to.be.true;
  		} );
  	} );
  
  	describe( 'rangeCount', () => {
  		it( 'should return proper range count', () => {
  			expect( selection.rangeCount ).to.equal( 1 );
  
  			selection._setTo( new Range( new Position( root, [ 0 ] ), new Position( root, [ 0 ] ) ) );
  
  			expect( selection.rangeCount ).to.equal( 1 );
  
  			selection._setTo( [
  				new Range( new Position( root, [ 2 ] ), new Position( root, [ 2 ] ) ),
  				new Range( new Position( root, [ 0 ] ), new Position( root, [ 0 ] ) )
  			] );
  
  			expect( selection.rangeCount ).to.equal( 2 );
  		} );
  	} );
  
  	describe( 'hasOwnRange', () => {
  		it( 'should return true if selection has any ranges set', () => {
  			selection._setTo( new Range( new Position( root, [ 0 ] ), new Position( root, [ 0 ] ) ) );
  
  			expect( selection.hasOwnRange ).to.be.true;
  		} );
  
  		it( 'should return false if selection has a default range', () => {
  			expect( selection.hasOwnRange ).to.be.false;
  		} );
  	} );
  
  	describe( 'markers', () => {
  		it( 'should implement #markers collection', () => {
  			expect( selection.markers ).to.instanceof( Collection );
  			expect( selection.markers ).to.length( 0 );
  		} );
  
  		it( 'should add markers to the collection when selection is inside the marker range', () => {
  			selection.observeMarkers( 'marker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 2 ] ),
  					writer.createPositionFromPath( root, [ 2, 4 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 0, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 2 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:2', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 2 ] ),
  						writer.createPositionFromPath( root, [ 2, 4 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:3', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 5 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:4', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 4 ] ),
  						writer.createPositionFromPath( root, [ 3, 0 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ) ).to.have.members( [ 'marker:2', 'marker:3' ] );
  		} );
  
  		it( 'should update markers after selection change', () => {
  			selection.observeMarkers( 'marker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 1 ] ),
  					writer.createPositionFromPath( root, [ 2, 2 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 6 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:2', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 3 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:3', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 3 ] ),
  						writer.createPositionFromPath( root, [ 2, 6 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ) ).to.have.members( [ 'marker:1', 'marker:2' ] );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 4 ] ),
  					writer.createPositionFromPath( root, [ 2, 5 ] )
  				) );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ) ).to.have.members( [ 'marker:1', 'marker:3' ] );
  		} );
  
  		it( 'should update markers after markers change', () => {
  			selection.observeMarkers( 'marker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 1 ] ),
  					writer.createPositionFromPath( root, [ 2, 2 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 6 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:2', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 3 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:3', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 3 ] ),
  						writer.createPositionFromPath( root, [ 2, 6 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ), 1 ).to.have.members( [ 'marker:1', 'marker:2' ] );
  
  			model.change( writer => {
  				writer.removeMarker( 'marker:1' );
  
  				writer.updateMarker( 'marker:2', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 3 ] ),
  						writer.createPositionFromPath( root, [ 2, 6 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.updateMarker( 'marker:3', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 3 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ), 2 ).to.have.members( [ 'marker:3' ] );
  		} );
  
  		it( 'should not add marker when collapsed selection is on the marker left bound', () => {
  			selection.observeMarkers( 'marker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 2 ] ),
  					writer.createPositionFromPath( root, [ 2, 4 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 2 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers ).to.length( 0 );
  		} );
  
  		it( 'should not add marker when collapsed selection is on the marker right bound', () => {
  			selection.observeMarkers( 'marker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 4 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 2 ] ),
  						writer.createPositionFromPath( root, [ 2, 4 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers ).to.length( 0 );
  		} );
  
  		it( 'should add marker when non-collapsed selection is inside a marker and touches the left bound', () => {
  			selection.observeMarkers( 'marker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 1 ] ),
  					writer.createPositionFromPath( root, [ 2, 3 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 5 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ) ).to.have.members( [ 'marker:1' ] );
  		} );
  
  		it( 'should add marker when non-collapsed selection is inside a marker and touches the right bound', () => {
  			selection.observeMarkers( 'marker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 2 ] ),
  					writer.createPositionFromPath( root, [ 2, 5 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 5 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ) ).to.have.members( [ 'marker:1' ] );
  		} );
  
  		it( 'should add marker of selected widget', () => {
  			selection.observeMarkers( 'marker' );
  
  			root._insertChild( 0, new Element( 'widget' ) );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 0 ] ),
  					writer.createPositionFromPath( root, [ 1 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 0 ] ),
  						writer.createPositionFromPath( root, [ 1 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ) ).to.have.members( [ 'marker:1' ] );
  		} );
  
  		it( 'should not add markers to the collection when markers observing is not enabled', () => {
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 2 ] ),
  					writer.createPositionFromPath( root, [ 2, 4 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 0, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 2 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:2', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 2 ] ),
  						writer.createPositionFromPath( root, [ 2, 4 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:3', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 5 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:4', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 4 ] ),
  						writer.createPositionFromPath( root, [ 3, 0 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers ).to.length( 0 );
  		} );
  
  		it( 'should add markers to the collection only for observed marker groups', () => {
  			selection.observeMarkers( 'marker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 2 ] ),
  					writer.createPositionFromPath( root, [ 2, 4 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 0, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 2 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'marker:2', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 2 ] ),
  						writer.createPositionFromPath( root, [ 2, 4 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'otherGroup:3', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 5 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'otherGroup:4', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 4 ] ),
  						writer.createPositionFromPath( root, [ 3, 0 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ) ).to.have.members( [ 'marker:2' ] );
  		} );
  
  		it( 'should add marker to the collection only for observed marker name', () => {
  			selection.observeMarkers( 'testMarker' );
  
  			model.change( writer => {
  				writer.setSelection( writer.createRange(
  					writer.createPositionFromPath( root, [ 2, 2 ] ),
  					writer.createPositionFromPath( root, [ 2, 4 ] )
  				) );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 0, 0 ] ),
  						writer.createPositionFromPath( root, [ 2, 2 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'testMarker', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 2 ] ),
  						writer.createPositionFromPath( root, [ 2, 4 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'otherMarker', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 5 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.addMarker( 'otherGroup:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 5 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			expect( selection.markers.map( marker => marker.name ) ).to.have.members( [ 'testMarker' ] );
  		} );
  
  		describe( 'should fire change:marker event when', () => {
  			// Set marker to range 0-4.
  			beforeEach( () => {
  				model.change( writer => {
  					writer.addMarker( 'marker:1', {
  						range: writer.createRange(
  							writer.createPositionFromPath( root, [ 2, 0 ] ),
  							writer.createPositionFromPath( root, [ 2, 4 ] )
  						),
  						usingOperation: false
  					} );
  				} );
  			} );
  
  			it( 'selection ranges change (marker added to the selection)', () => {
  				const spy = sinon.spy();
  
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					// The selection has no markers before the change.
  					model.document.selection.on( 'change:marker', ( evt, data ) => {
  						expect( data.oldMarkers ).to.deep.equal( [] );
  						spy();
  					} );
  
  					// Move selection to 1-2, that is inside 0-4 marker.
  					writer.setSelection( writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 2 ] )
  					) );
  				} );
  
  				expect( spy.calledOnce ).to.be.true;
  			} );
  
  			it( 'selection ranges change (marker removed from the selection)', () => {
  				const spy = sinon.spy();
  
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					writer.setSelection( writer.createRange(
  						writer.createPositionFromPath( root, [ 2, 1 ] ),
  						writer.createPositionFromPath( root, [ 2, 2 ] )
  					) );
  
  					// The selection is in a marker before the change.
  					model.document.selection.on( 'change:marker', ( evt, data ) => {
  						expect( data.oldMarkers.map( marker => marker.name ) ).to.deep.equal( [ 'marker:1' ] );
  						spy();
  					} );
  
  					// Move the selection out of the marker.
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 5 ] ) );
  				} );
  
  				expect( spy.calledOnce ).to.be.true;
  			} );
  
  			it( 'selection focus changes (marker removed from the selection)', () => {
  				const spy = sinon.spy();
  
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 2 ] ) );
  
  					// The selection is in a marker before the change.
  					model.document.selection.on( 'change:marker', ( evt, data ) => {
  						expect( data.oldMarkers.map( marker => marker.name ) ).to.deep.equal( [ 'marker:1' ] );
  						spy();
  					} );
  
  					// Move the selection focus out of the marker.
  					writer.setSelectionFocus( writer.createPositionFromPath( root, [ 2, 5 ] ) );
  				} );
  
  				expect( spy.calledOnce ).to.be.true;
  			} );
  
  			it( 'a new marker contains the selection', () => {
  				const spy = sinon.spy();
  
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 5 ] ) );
  
  					// The selection is not in a marker before the change.
  					model.document.selection.on( 'change:marker', ( evt, data ) => {
  						expect( data.oldMarkers ).to.deep.equal( [] );
  						spy();
  					} );
  
  					writer.updateMarker( 'marker:1', {
  						range: writer.createRange(
  							writer.createPositionFromPath( root, [ 2, 0 ] ),
  							writer.createPositionFromPath( root, [ 2, 6 ] )
  						)
  					} );
  				} );
  
  				expect( spy.calledOnce ).to.be.true;
  			} );
  
  			it( 'a marker stops contains the selection', () => {
  				const spy = sinon.spy();
  
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 3 ] ) );
  
  					// The selection is in a marker before the change.
  					model.document.selection.on( 'change:marker', ( evt, data ) => {
  						expect( data.oldMarkers.map( marker => marker.name ) ).to.deep.equal( [ 'marker:1' ] );
  						spy();
  					} );
  
  					writer.updateMarker( 'marker:1', {
  						range: writer.createRange(
  							writer.createPositionFromPath( root, [ 2, 0 ] ),
  							writer.createPositionFromPath( root, [ 2, 1 ] )
  						)
  					} );
  				} );
  
  				expect( spy.calledOnce ).to.be.true;
  			} );
  		} );
  
  		describe( 'should not fire change:marker event when', () => {
  			// Set marker to range 0-4.
  			beforeEach( () => {
  				model.change( writer => {
  					writer.addMarker( 'marker:1', {
  						range: writer.createRange(
  							writer.createPositionFromPath( root, [ 2, 0 ] ),
  							writer.createPositionFromPath( root, [ 2, 4 ] )
  						),
  						usingOperation: false
  					} );
  				} );
  			} );
  
  			it( 'selection ranges change does not change selection markers (no markers)', () => {
  				const spy = sinon.spy();
  
  				selection.observeMarkers( 'marker' );
  
  				model.document.selection.on( 'change:marker', spy );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 5 ] ) );
  				} );
  
  				expect( spy.called ).to.be.false;
  			} );
  
  			it( 'selection ranges change does not change selection markers (same markers)', () => {
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 2 ] ) );
  				} );
  
  				const spy = sinon.spy();
  
  				model.document.selection.on( 'change:marker', spy );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 3 ] ) );
  				} );
  
  				expect( spy.called ).to.be.false;
  			} );
  
  			it( 'selection focus change does not change selection markers', () => {
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 2 ] ) );
  				} );
  
  				const spy = sinon.spy();
  
  				model.document.selection.on( 'change:marker', spy );
  
  				model.change( writer => {
  					writer.setSelectionFocus( writer.createPositionFromPath( root, [ 2, 3 ] ) );
  				} );
  
  				expect( spy.called ).to.be.false;
  			} );
  
  			it( 'changed marker still contains the selection', () => {
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 2 ] ) );
  				} );
  
  				const spy = sinon.spy();
  
  				model.document.selection.on( 'change:marker', spy );
  
  				model.change( writer => {
  					writer.updateMarker( 'marker:1', {
  						range: writer.createRange(
  							writer.createPositionFromPath( root, [ 2, 0 ] ),
  							writer.createPositionFromPath( root, [ 2, 5 ] )
  						)
  					} );
  				} );
  
  				expect( spy.called ).to.be.false;
  			} );
  
  			it( 'removed marker did not contain the selection', () => {
  				selection.observeMarkers( 'marker' );
  
  				model.change( writer => {
  					writer.setSelection( writer.createPositionFromPath( root, [ 2, 5 ] ) );
  				} );
  
  				const spy = sinon.spy();
  
  				model.document.selection.on( 'change:marker', spy );
  
  				model.change( writer => {
  					writer.removeMarker( 'marker:1' );
  				} );
  
  				expect( spy.called ).to.be.false;
  			} );
  		} );
  	} );
  
  	describe( 'destroy()', () => {
  		it( 'should unbind all events', () => {
  			selection._setTo( [ range, liveRange ] );
  
  			const ranges = Array.from( selection._selection._ranges );
  
  			sinon.spy( ranges[ 0 ], 'detach' );
  			sinon.spy( ranges[ 1 ], 'detach' );
  
  			selection.destroy();
  
  			expect( ranges[ 0 ].detach.called ).to.be.true;
  			expect( ranges[ 1 ].detach.called ).to.be.true;
  		} );
  	} );
  
  	describe( 'getFirstRange()', () => {
  		it( 'should return default range if no ranges were added', () => {
  			const firstRange = selection.getFirstRange();
  
  			expect( firstRange.start.isEqual( new Position( root, [ 0, 0 ] ) ) );
  			expect( firstRange.end.isEqual( new Position( root, [ 0, 0 ] ) ) );
  		} );
  	} );
  
  	describe( 'getLastRange()', () => {
  		it( 'should return default range if no ranges were added', () => {
  			const lastRange = selection.getLastRange();
  
  			expect( lastRange.start.isEqual( new Position( root, [ 0, 0 ] ) ) );
  			expect( lastRange.end.isEqual( new Position( root, [ 0, 0 ] ) ) );
  		} );
  	} );
  
  	describe( 'getSelectedElement()', () => {
  		it( 'should return selected element', () => {
  			selection._setTo( liveRange );
  			const p = root.getChild( 0 );
  
  			expect( selection.getSelectedElement() ).to.equal( p );
  		} );
  	} );
  
  	describe( 'is()', () => {
  		it( 'should return true for selection', () => {
  			expect( selection.is( 'selection' ) ).to.be.true;
  			expect( selection.is( 'model:selection' ) ).to.be.true;
  		} );
  
  		it( 'should return true for documentSelection', () => {
  			expect( selection.is( 'documentSelection' ) ).to.be.true;
  			expect( selection.is( 'model:documentSelection' ) ).to.be.true;
  		} );
  
  		it( 'should return false for other values', () => {
  			expect( selection.is( 'node' ) ).to.be.false;
  			expect( selection.is( 'model:node' ) ).to.be.false;
  			expect( selection.is( '$text' ) ).to.be.false;
  			expect( selection.is( '$textProxy' ) ).to.be.false;
  			expect( selection.is( 'element' ) ).to.be.false;
  			expect( selection.is( 'element', 'paragraph' ) ).to.be.false;
  			expect( selection.is( 'rootElement' ) ).to.be.false;
  			expect( selection.is( 'view:selection' ) ).to.be.false;
  			expect( selection.is( 'view:documentSelection' ) ).to.be.false;
  		} );
  	} );
  
  	describe( '_setTo() - set collapsed at', () => {
  		it( 'detaches all existing ranges', () => {
  			selection._setTo( [ range, liveRange ] );
  
  			const spy = sinon.spy( LiveRange.prototype, 'detach' );
  			selection._setTo( root, 0 );
  
  			expect( spy.calledTwice ).to.be.true;
  		} );
  	} );
  
  	describe( '_setFocus()', () => {
  		it( 'modifies default range', () => {
  			const startPos = selection.getFirstPosition();
  			const endPos = Position._createAt( root, 'end' );
  
  			selection._setFocus( endPos );
  
  			expect( selection.anchor.compareWith( startPos ) ).to.equal( 'same' );
  			expect( selection.focus.compareWith( endPos ) ).to.equal( 'same' );
  		} );
  
  		it( 'detaches the range it replaces', () => {
  			const startPos = Position._createAt( root, 1 );
  			const endPos = Position._createAt( root, 2 );
  			const newEndPos = Position._createAt( root, 4 );
  			const spy = sinon.spy( LiveRange.prototype, 'detach' );
  
  			selection._setTo( new Range( startPos, endPos ) );
  
  			selection._setFocus( newEndPos );
  
  			expect( spy.calledOnce ).to.be.true;
  		} );
  
  		it( 'refreshes attributes', () => {
  			const spy = sinon.spy( selection._selection, '_updateAttributes' );
  
  			selection._setFocus( Position._createAt( root, 1 ) );
  
  			expect( spy.called ).to.be.true;
  		} );
  	} );
  
  	describe( '_setTo() - remove all ranges', () => {
  		let spy, ranges;
  
  		beforeEach( () => {
  			selection._setTo( [ liveRange, range ] );
  
  			spy = sinon.spy();
  			selection.on( 'change:range', spy );
  
  			ranges = Array.from( selection._selection._ranges );
  
  			sinon.spy( ranges[ 0 ], 'detach' );
  			sinon.spy( ranges[ 1 ], 'detach' );
  
  			selection._setTo( null );
  		} );
  
  		it( 'should remove all stored ranges (and reset to default range)', () => {
  			expect( Array.from( selection.getRanges() ).length ).to.equal( 1 );
  			expect( selection.anchor.isEqual( new Position( root, [ 0, 0 ] ) ) ).to.be.true;
  			expect( selection.focus.isEqual( new Position( root, [ 0, 0 ] ) ) ).to.be.true;
  		} );
  
  		it( 'should detach ranges', () => {
  			expect( ranges[ 0 ].detach.called ).to.be.true;
  			expect( ranges[ 1 ].detach.called ).to.be.true;
  		} );
  
  		it( 'should refresh attributes', () => {
  			const spy = sinon.spy( selection._selection, '_updateAttributes' );
  
  			selection._setTo( null );
  
  			expect( spy.called ).to.be.true;
  		} );
  	} );
  
  	describe( '_setTo()', () => {
  		it( 'should throw an error when range is invalid', () => {
  			expectToThrowCKEditorError( () => {
  				selection._setTo( [ { invalid: 'range' } ] );
  			}, /model-selection-set-ranges-not-range/, model );
  		} );
  
  		it( 'should do nothing when trying to set selection to the graveyard', () => {
  			// Catches the 'Trying to add a Range that is in the graveyard root. Range rejected.' warning in the CK_DEBUG mode.
  			sinon.stub( console, 'warn' );
  
  			const range = new Range( new Position( model.document.graveyard, [ 0 ] ) );
  			selection._setTo( range );
  
  			expect( selection._ranges ).to.deep.equal( [] );
  		} );
  
  		it( 'should detach removed ranges', () => {
  			selection._setTo( [ liveRange, range ] );
  
  			const oldRanges = Array.from( selection._selection._ranges );
  
  			sinon.spy( oldRanges[ 0 ], 'detach' );
  			sinon.spy( oldRanges[ 1 ], 'detach' );
  
  			selection._setTo( [] );
  
  			expect( oldRanges[ 0 ].detach.called ).to.be.true;
  			expect( oldRanges[ 1 ].detach.called ).to.be.true;
  		} );
  
  		it( 'should refresh attributes', () => {
  			const spy = sinon.spy( selection._selection, '_updateAttributes' );
  
  			selection._setTo( [ range ] );
  
  			expect( spy.called ).to.be.true;
  		} );
  
  		// See #630.
  		it( 'should refresh attributes – integration test for #630', () => {
  			model.schema.extend( '$text', { allowIn: '$root' } );
  
  			setData( model, 'f<$text italic="true">[o</$text><$text bold="true">ob]a</$text>r' );
  
  			selection._setTo( [ Range._createFromPositionAndShift( selection.getLastRange().end, 0 ) ] );
  
  			expect( selection.getAttribute( 'bold' ) ).to.equal( true );
  			expect( selection.hasAttribute( 'italic' ) ).to.equal( false );
  
  			expect( getData( model ) )
  				.to.equal( 'f<$text italic="true">o</$text><$text bold="true">ob[]a</$text>r' );
  		} );
  	} );
  
  	describe( '_isStoreAttributeKey', () => {
  		it( 'should return true if given key is a key of an attribute stored in element by DocumentSelection', () => {
  			expect( DocumentSelection._isStoreAttributeKey( fooStoreAttrKey ) ).to.be.true;
  		} );
  
  		it( 'should return false if given key is not a key of an attribute stored in element by DocumentSelection', () => {
  			expect( DocumentSelection._isStoreAttributeKey( 'foo' ) ).to.be.false;
  		} );
  	} );
  
  	describe( 'attributes', () => {
  		let fullP, emptyP, rangeInFullP, rangeInEmptyP;
  
  		beforeEach( () => {
  			root._removeChildren( 0, root.childCount );
  			root._appendChild( [
  				new Element( 'p', [], new Text( 'foobar' ) ),
  				new Element( 'p', [], [] )
  			] );
  
  			fullP = root.getChild( 0 );
  			emptyP = root.getChild( 1 );
  
  			rangeInFullP = new Range( new Position( root, [ 0, 4 ] ), new Position( root, [ 0, 4 ] ) );
  			rangeInEmptyP = new Range( new Position( root, [ 1, 0 ] ), new Position( root, [ 1, 0 ] ) );
  
  			// I've lost 30 mins debugging why my tests fail and that was due to the above code reusing
  			// a root which wasn't empty (so the ranges didn't actually make much sense).
  			expect( root.childCount ).to.equal( 2 );
  		} );
  
  		describe( '_setAttribute()', () => {
  			it( 'should set attribute', () => {
  				selection._setTo( [ rangeInEmptyP ] );
  				selection._setAttribute( 'foo', 'bar' );
  
  				expect( selection.getAttribute( 'foo' ) ).to.equal( 'bar' );
  			} );
  		} );
  
  		describe( '_removeAttribute()', () => {
  			it( 'should remove attribute set on the text fragment', () => {
  				selection._setTo( [ rangeInFullP ] );
  				selection._setAttribute( 'foo', 'bar' );
  				selection._removeAttribute( 'foo' );
  
  				expect( selection.getAttribute( 'foo' ) ).to.be.undefined;
  			} );
  
  			it( 'should prevent auto update of the attribute even if attribute is not preset yet', () => {
  				selection._setTo( new Position( root, [ 0, 1 ] ) );
  
  				// Remove "foo" attribute that is not present in selection yet.
  				expect( selection.hasAttribute( 'foo' ) ).to.be.false;
  				selection._removeAttribute( 'foo' );
  
  				// Trigger selecton auto update on document change. It should not get attribute from surrounding text;
  				model.change( writer => {
  					writer.setAttribute( 'foo', 'bar', Range._createIn( fullP ) );
  				} );
  
  				expect( selection.getAttribute( 'foo' ) ).to.be.undefined;
  			} );
  		} );
  
  		describe( '_getStoredAttributes()', () => {
  			it( 'should return no values if there are no ranges in selection', () => {
  				const values = Array.from( selection._getStoredAttributes() );
  
  				expect( values ).to.deep.equal( [] );
  			} );
  		} );
  
  		describe( 'are updated on a direct range change', () => {
  			beforeEach( () => {
  				root._insertChild( 0, [
  					new Element( 'p', { p: true } ),
  					new Text( 'a', { a: true } ),
  					new Element( 'p', { p: true } ),
  					new Text( 'b', { b: true } ),
  					new Text( 'c', { c: true } ),
  					new Element( 'p', [], [
  						new Text( 'd', { d: true } )
  					] ),
  					new Element( 'p', { p: true } ),
  					new Text( 'e', { e: true } )
  				] );
  			} );
  
  			it( 'if selection is a range, should find first character in it and copy it\'s attributes', () => {
  				selection._setTo( [ new Range( new Position( root, [ 2 ] ), new Position( root, [ 5 ] ) ) ] );
  
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'b', true ] ] );
  
  				// Step into elements when looking for first character:
  				selection._setTo( [ new Range( new Position( root, [ 5 ] ), new Position( root, [ 7 ] ) ) ] );
  
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'd', true ] ] );
  			} );
  
  			it( 'if selection is collapsed it should seek a character to copy that character\'s attributes', () => {
  				// Take styles from character before selection.
  				selection._setTo( [ new Range( new Position( root, [ 2 ] ), new Position( root, [ 2 ] ) ) ] );
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'a', true ] ] );
  
  				// If there are none,
  				// Take styles from character after selection.
  				selection._setTo( [ new Range( new Position( root, [ 3 ] ), new Position( root, [ 3 ] ) ) ] );
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'b', true ] ] );
  
  				// If there are none,
  				// Look from the selection position to the beginning of node looking for character to take attributes from.
  				selection._setTo( [ new Range( new Position( root, [ 6 ] ), new Position( root, [ 6 ] ) ) ] );
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'c', true ] ] );
  
  				// If there are none,
  				// Look from the selection position to the end of node looking for character to take attributes from.
  				selection._setTo( [ new Range( new Position( root, [ 0 ] ), new Position( root, [ 0 ] ) ) ] );
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'a', true ] ] );
  
  				// If there are no characters to copy attributes from, use stored attributes.
  				selection._setTo( [ new Range( new Position( root, [ 0, 0 ] ), new Position( root, [ 0, 0 ] ) ) ] );
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [] );
  			} );
  
  			it( 'should overwrite any previously set attributes', () => {
  				selection._setTo( new Position( root, [ 5, 0 ] ) );
  
  				selection._setAttribute( 'x', true );
  				selection._setAttribute( 'y', true );
  
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'd', true ], [ 'x', true ], [ 'y', true ] ] );
  
  				selection._setTo( new Position( root, [ 1 ] ) );
  
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'a', true ] ] );
  			} );
  
  			it( 'should fire change:attribute event', () => {
  				const spy = sinon.spy();
  				selection.on( 'change:attribute', spy );
  
  				selection._setTo( [ new Range( new Position( root, [ 2 ] ), new Position( root, [ 5 ] ) ) ] );
  
  				expect( spy.calledOnce ).to.be.true;
  			} );
  
  			it( 'should not fire change:attribute event if attributes did not change', () => {
  				selection._setTo( new Position( root, [ 5, 0 ] ) );
  
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'd', true ] ] );
  
  				const spy = sinon.spy();
  				selection.on( 'change:attribute', spy );
  
  				selection._setTo( new Position( root, [ 5, 1 ] ) );
  
  				expect( Array.from( selection.getAttributes() ) ).to.deep.equal( [ [ 'd', true ] ] );
  				expect( spy.called ).to.be.false;
  			} );
  		} );
  
  		// #986
  		describe( 'are not inherited from the inside of object elements', () => {
  			beforeEach( () => {
  				model.schema.register( 'imageBlock', {
  					isObject: true
  				} );
  				model.schema.extend( 'imageBlock', { allowIn: '$root' } );
  				model.schema.extend( 'imageBlock', { allowIn: '$block' } );
  
  				model.schema.register( 'caption' );
  				model.schema.extend( 'caption', { allowIn: 'imageBlock' } );
  				model.schema.extend( '$text', {
  					allowIn: [ 'imageBlock', 'caption' ],
  					allowAttributes: 'bold'
  				} );
  			} );
  
  			it( 'ignores attributes inside an object if selection contains that object', () => {
  				setData( model, '<p>[<imageBlock><$text bold="true">Caption for the image.</$text></imageBlock>]</p>' );
  
  				expect( selection.hasAttribute( 'bold' ) ).to.equal( false );
  			} );
  
  			it( 'ignores attributes inside an object if selection contains that object (deeper structure)', () => {
  				setData( model, '<p>[<imageBlock><caption><$text bold="true">Caption for the image.</$text></caption></imageBlock>]</p>' );
  
  				expect( selection.hasAttribute( 'bold' ) ).to.equal( false );
  			} );
  
  			it( 'ignores attributes inside an object if selection contains that object (block level)', () => {
  				setData( model, '<p>foo</p>[<imageBlock><$text bold="true">Caption for the image.</$text></imageBlock>]<p>foo</p>' );
  
  				expect( selection.hasAttribute( 'bold' ) ).to.equal( false );
  			} );
  
  			it( 'reads attributes from text even if the selection contains an object', () => {
  				setData( model, '<p>x<$text bold="true">[bar</$text><imageBlock></imageBlock>foo]</p>' );
  
  				expect( selection.getAttribute( 'bold' ) ).to.equal( true );
  			} );
  
  			it( 'reads attributes when the entire selection inside an object', () => {
  				setData( model, '<p><imageBlock><caption><$text bold="true">[bar]</$text></caption></imageBlock></p>' );
  
  				expect( selection.getAttribute( 'bold' ) ).to.equal( true );
  			} );
  
  			it( 'stops reading attributes if selection starts with an object', () => {
  				setData( model, '<p>[<imageBlock></imageBlock><$text bold="true">bar]</$text></p>' );
  
  				expect( selection.hasAttribute( 'bold' ) ).to.equal( false );
  			} );
  		} );
  
  		describe( 'parent element\'s attributes', () => {
  			it( 'are set using a normal batch', () => {
  				let batch;
  
  				model.once( 'applyOperation', ( event, args ) => {
  					const operation = args[ 0 ];
  					batch = operation.batch;
  				} );
  
  				selection._setTo( [ rangeInEmptyP ] );
  
  				model.change( writer => {
  					writer.setSelectionAttribute( 'foo', 'bar' );
  				} );
  
  				expect( batch.isUndoable ).to.be.true;
  
  				expect( emptyP.getAttribute( fooStoreAttrKey ) ).to.equal( 'bar' );
  			} );
  
  			it( 'are removed when any content is inserted (reuses the same batch)', () => {
  				const batches = new Set();
  
  				selection._setTo( rangeInEmptyP );
  				selection._setAttribute( 'foo', 'bar' );
  				selection._setAttribute( 'abc', 'bar' );
  
  				model.on( 'applyOperation', ( event, args ) => {
  					const operation = args[ 0 ];
  					const batch = operation.batch;
  
  					batches.add( batch );
  				} );
  
  				model.change( writer => {
  					writer.insertText( 'x', rangeInEmptyP.start );
  				} );
  
  				expect( emptyP.hasAttribute( fooStoreAttrKey ) ).to.be.false;
  				expect( emptyP.hasAttribute( abcStoreAttrKey ) ).to.be.false;
  
  				expect( batches.size ).to.equal( 1 );
  
  				const batch = Array.from( batches )[ 0 ];
  
  				expect( batch.isUndoable ).to.be.true;
  			} );
  
  			it( 'are removed when any content is moved into', () => {
  				selection._setTo( rangeInEmptyP );
  				selection._setAttribute( 'foo', 'bar' );
  
  				model.change( writer => {
  					writer.move( writer.createRangeOn( fullP.getChild( 0 ) ), rangeInEmptyP.start );
  				} );
  
  				expect( emptyP.hasAttribute( fooStoreAttrKey ) ).to.be.false;
  			} );
  
  			it( 'are removed when containing element is merged with a non-empty element', () => {
  				const emptyP2 = new Element( 'p', null, 'x' );
  				root._appendChild( emptyP2 );
  
  				emptyP._setAttribute( fooStoreAttrKey, 'bar' );
  				emptyP2._setAttribute( fooStoreAttrKey, 'bar' );
  
  				model.change( writer => {
  					// <emptyP>{}<emptyP2>
  					writer.merge( writer.createPositionAfter( emptyP ) );
  				} );
  
  				expect( emptyP.hasAttribute( fooStoreAttrKey ) ).to.be.false;
  				expect( emptyP.parent ).to.equal( root ); // Just to be sure we're checking the right element.
  			} );
  
  			it( 'are removed even when there is no selection in it', () => {
  				emptyP._setAttribute( fooStoreAttrKey, 'bar' );
  
  				selection._setTo( [ rangeInFullP ] );
  
  				model.change( writer => {
  					writer.insertText( 'x', rangeInEmptyP.start );
  				} );
  
  				expect( emptyP.hasAttribute( fooStoreAttrKey ) ).to.be.false;
  			} );
  
  			it( 'uses model change to clear attributes', () => {
  				selection._setTo( [ rangeInEmptyP ] );
  
  				model.change( writer => {
  					writer.setSelectionAttribute( 'foo', 'bar' );
  					writer.insertText( 'x', rangeInEmptyP.start );
  
  					// `emptyP` still has the attribute, because attribute clearing is in enqueued block.
  					expect( emptyP.hasAttribute( fooStoreAttrKey ) ).to.be.true;
  				} );
  
  				// When the dust settles, `emptyP` should not have the attribute.
  				expect( emptyP.hasAttribute( fooStoreAttrKey ) ).to.be.false;
  			} );
  
  			it( 'are not removed or merged when containing element is merged with another empty element', () => {
  				const emptyP2 = new Element( 'p', null );
  				root._appendChild( emptyP2 );
  
  				emptyP._setAttribute( fooStoreAttrKey, 'bar' );
  				emptyP2._setAttribute( abcStoreAttrKey, 'bar' );
  
  				expect( emptyP.hasAttribute( fooStoreAttrKey ) ).to.be.true;
  				expect( emptyP.hasAttribute( abcStoreAttrKey ) ).to.be.false;
  
  				model.change( writer => {
  					// <emptyP>{}<emptyP2>
  					writer.merge( writer.createPositionAfter( emptyP ) );
  				} );
  
  				expect( emptyP.getAttribute( fooStoreAttrKey ) ).to.equal( 'bar' );
  				expect( emptyP.parent ).to.equal( root ); // Just to be sure we're checking the right element.
  			} );
  
  			// Rename and some other operations don't specify range in doc#change event.
  			// So let's see if there's no crash or something.
  			it( 'are not removed on rename', () => {
  				model.change( writer => {
  					writer.setSelection( rangeInEmptyP );
  					writer.setSelectionAttribute( 'foo', 'bar' );
  				} );
  
  				sinon.spy( model, 'enqueueChange' );
  
  				model.change( writer => {
  					writer.rename( emptyP, 'pnew' );
  				} );
  
  				expect( model.enqueueChange.called ).to.be.false;
  				expect( emptyP.getAttribute( fooStoreAttrKey ) ).to.equal( 'bar' );
  			} );
  		} );
  
  		// #7459
  		describe( 'ignores inline elements while reading surrounding attributes', () => {
  			beforeEach( () => {
  				model.schema.register( 'softBreak', {
  					allowWhere: '$text',
  					isInline: true
  				} );
  			} );
  
  			it( 'should not inherit attributes from a node before an inline element', () => {
  				setData( model, '<p><$text bold="true">Foo Bar.</$text><softBreak></softBreak>[]</p>' );
  
  				expect( selection.hasAttribute( 'bold' ) ).to.equal( false );
  			} );
  
  			it( 'should not inherit attributes from a node after an inline element (override gravity)', () => {
  				setData( model, '<p>[]<softBreak></softBreak><$text bold="true">Foo Bar.</$text></p>' );
  
  				const overrideGravityUid = selection._overrideGravity();
  
  				expect( selection.hasAttribute( 'bold' ) ).to.equal( false );
  
  				selection._restoreGravity( overrideGravityUid );
  			} );
  		} );
  	} );
  
  	describe( '_overrideGravity()', () => {
  		beforeEach( () => {
  			model.schema.extend( '$text', {
  				allowIn: '$root'
  			} );
  		} );
  
  		it( 'should return the UID', () => {
  			const overrideUidA = selection._overrideGravity();
  			const overrideUidB = selection._overrideGravity();
  
  			expect( overrideUidA ).to.be.a( 'string' );
  			expect( overrideUidB ).to.be.a( 'string' );
  			expect( overrideUidA ).to.not.equal( overrideUidB );
  		} );
  
  		it( 'should mark gravity as overridden', () => {
  			expect( selection.isGravityOverridden ).to.false;
  
  			selection._overrideGravity();
  
  			expect( selection.isGravityOverridden ).to.true;
  		} );
  
  		it( 'should not inherit attributes from node before the caret', () => {
  			setData( model, '<$text bold="true" italic="true">foo[]</$text>' );
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.have.members( [ 'bold', 'italic' ] );
  
  			selection._overrideGravity();
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.length( 0 );
  		} );
  
  		it( 'should inherit attributes from node after the caret', () => {
  			setData( model, '<$text>foo[]</$text><$text bold="true" italic="true">bar</$text>' );
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.length( 0 );
  
  			selection._overrideGravity();
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.have.members( [ 'bold', 'italic' ] );
  		} );
  
  		it( 'should not retain attributes that are set explicitly', () => {
  			setData( model, '<$text italic="true">foo[]</$text>' );
  
  			selection._setAttribute( 'bold', true );
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.have.members( [ 'bold', 'italic' ] );
  
  			selection._overrideGravity();
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.have.members( [] );
  		} );
  
  		it( 'should retain overridden until selection will not change range by a direct change', () => {
  			setData( model, '<$text bold="true" italic="true">foo[]</$text><$text italic="true">bar</$text>' );
  
  			selection._overrideGravity();
  
  			// Changed range but not directly.
  			model.change( writer => writer.insertText( 'abc', new Position( root, [ 0 ] ) ) );
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.have.members( [ 'italic' ] );
  
  			// Changed range directly.
  			model.change( writer => writer.setSelection( new Position( root, [ 5 ] ) ) );
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.have.members( [ 'bold', 'italic' ] );
  		} );
  	} );
  
  	describe( '_restoreGravity()', () => {
  		beforeEach( () => {
  			model.schema.extend( '$text', {
  				allowIn: '$root'
  			} );
  		} );
  
  		it( 'should throw when a wrong, already restored, or no UID provided', () => {
  			const overrideUid = selection._overrideGravity();
  			selection._restoreGravity( overrideUid );
  
  			// Wrong UID
  			expectToThrowCKEditorError( () => {
  				selection._restoreGravity( 'foo' );
  			}, /^document-selection-gravity-wrong-restore/, model );
  
  			// Already restored
  			expectToThrowCKEditorError( () => {
  				selection._restoreGravity( overrideUid );
  			}, /^document-selection-gravity-wrong-restore/, model );
  
  			// No UID
  			expectToThrowCKEditorError( () => {
  				selection._restoreGravity();
  			}, /^document-selection-gravity-wrong-restore/, model );
  		} );
  
  		it( 'should revert default gravity when is overridden', () => {
  			setData( model, '<$text bold="true" italic="true">foo[]</$text>' );
  
  			const overrideUid = selection._overrideGravity();
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.length( 0 );
  			expect( selection.isGravityOverridden ).to.true;
  
  			selection._restoreGravity( overrideUid );
  
  			expect( Array.from( selection.getAttributeKeys() ) ).to.have.members( [ 'bold', 'italic' ] );
  			expect( selection.isGravityOverridden ).to.false;
  		} );
  
  		it( 'should be called the same number of times as gravity is overridden to restore it', () => {
  			setData( model, '<$text bold="true" italic="true">foo[]</$text>' );
  
  			const overrideUidA = selection._overrideGravity();
  			const overrideUidB = selection._overrideGravity();
  
  			expect( selection.isGravityOverridden ).to.true;
  
  			selection._restoreGravity( overrideUidA );
  
  			expect( selection.isGravityOverridden ).to.true;
  
  			selection._restoreGravity( overrideUidB );
  
  			expect( selection.isGravityOverridden ).to.false;
  		} );
  	} );
  
  	// https://github.com/ckeditor/ckeditor5-engine/issues/1673
  	describe( 'refreshing selection data', () => {
  		it( 'should be up to date before post fixers', () => {
  			model.schema.extend( '$text', { allowAttributes: 'foo' } );
  
  			const p = doc.getRoot().getChild( 0 );
  
  			selection.observeMarkers( 'marker' );
  
  			doc.registerPostFixer( () => {
  				expect( model.document.selection.getAttribute( 'foo' ) ).to.equal( 'bar' );
  				expect( Array.from( model.document.selection.markers, m => m.name ) ).to.deep.equal( [ 'marker:1' ] );
  			} );
  
  			model.change( writer => {
  				writer.insertText( 'abcdef', { foo: 'bar' }, p );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( p, [ 1 ] ),
  						writer.createPositionFromPath( p, [ 5 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.setSelection( writer.createPositionFromPath( p, [ 3 ] ) );
  			} );
  		} );
  
  		it( 'should be up to date between post fixers', () => {
  			model.schema.extend( '$text', { allowAttributes: 'foo' } );
  
  			const p = doc.getRoot().getChild( 0 );
  
  			selection.observeMarkers( 'marker' );
  
  			doc.registerPostFixer( writer => {
  				writer.setAttribute( 'foo', 'biz', p.getChild( 0 ) );
  				writer.removeMarker( 'marker:1' );
  				writer.addMarker( 'marker:2', {
  					range: writer.createRange(
  						writer.createPositionFromPath( p, [ 1 ] ),
  						writer.createPositionFromPath( p, [ 5 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			doc.registerPostFixer( () => {
  				expect( model.document.selection.getAttribute( 'foo' ) ).to.equal( 'biz' );
  				expect( Array.from( model.document.selection.markers, m => m.name ) ).to.deep.equal( [ 'marker:2' ] );
  			} );
  
  			model.change( writer => {
  				writer.insertText( 'abcdef', { foo: 'bar' }, p );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( p, [ 1 ] ),
  						writer.createPositionFromPath( p, [ 5 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.setSelection( writer.createPositionFromPath( p, [ 3 ] ) );
  			} );
  		} );
  
  		it( 'should be up to date after post fixers (on `change` event)', done => {
  			model.schema.extend( '$text', { allowAttributes: 'foo' } );
  
  			const p = doc.getRoot().getChild( 0 );
  
  			selection.observeMarkers( 'marker' );
  
  			doc.on( 'change', () => {
  				expect( model.document.selection.getAttribute( 'foo' ) ).to.equal( 'biz' );
  				expect( Array.from( model.document.selection.markers, m => m.name ) ).to.deep.equal( [ 'marker:2' ] );
  				done();
  			} );
  
  			doc.registerPostFixer( writer => {
  				writer.setAttribute( 'foo', 'biz', p.getChild( 0 ) );
  				writer.removeMarker( 'marker:1' );
  				writer.addMarker( 'marker:2', {
  					range: writer.createRange(
  						writer.createPositionFromPath( p, [ 1 ] ),
  						writer.createPositionFromPath( p, [ 5 ] )
  					),
  					usingOperation: false
  				} );
  			} );
  
  			model.change( writer => {
  				writer.insertText( 'abcdef', { foo: 'bar' }, p );
  
  				writer.addMarker( 'marker:1', {
  					range: writer.createRange(
  						writer.createPositionFromPath( p, [ 1 ] ),
  						writer.createPositionFromPath( p, [ 5 ] )
  					),
  					usingOperation: false
  				} );
  
  				writer.setSelection( writer.createPositionFromPath( p, [ 3 ] ) );
  			} );
  		} );
  	} );
  
  	// DocumentSelection uses LiveRanges so here are only simple test to see if integration is
  	// working well, without getting into complicated corner cases.
  	describe( 'after applying an operation should get updated and fire events', () => {
  		let spyRange;
  
  		beforeEach( () => {
  			root._removeChildren( 0, root.childCount );
  			root._insertChild( 0, [
  				new Element( 'p', [], new Text( 'abcdef' ) ),
  				new Element( 'p', [], new Text( 'foobar' ) ),
  				new Text( 'xyz' )
  			] );
  
  			selection._setTo( new Range( new Position( root, [ 0, 2 ] ), new Position( root, [ 1, 4 ] ) ) );
  
  			spyRange = sinon.spy();
  			selection.on( 'change:range', spyRange );
  		} );
  
  		describe( 'InsertOperation', () => {
  			it( 'before selection', () => {
  				selection.on( 'change:range', ( evt, data ) => {
  					expect( data.directChange ).to.be.false;
  				} );
  
  				model.applyOperation(
  					new InsertOperation(
  						new Position( root, [ 0, 1 ] ),
  						'xyz',
  						doc.version
  					)
  				);
  
  				const range = selection.getFirstRange();
  
  				expect( range.start.path ).to.deep.equal( [ 0, 5 ] );
  				expect( range.end.path ).to.deep.equal( [ 1, 4 ] );
  				expect( spyRange.calledOnce ).to.be.true;
  			} );
  
  			it( 'inside selection', () => {
  				selection.on( 'change:range', ( evt, data ) => {
  					expect( data.directChange ).to.be.false;
  				} );
  
  				model.applyOperation(
  					new InsertOperation(
  						new Position( root, [ 1, 0 ] ),
  						'xyz',
  						doc.version
  					)
  				);
  
  				const range = selection.getFirstRange();
  
  				expect( range.start.path ).to.deep.equal( [ 0, 2 ] );
  				expect( range.end.path ).to.deep.equal( [ 1, 7 ] );
  				expect( spyRange.calledOnce ).to.be.true;
  			} );
  		} );
  
  		describe( 'MoveOperation', () => {
  			it( 'move range from before a selection', () => {
  				selection.on( 'change:range', ( evt, data ) => {
  					expect( data.directChange ).to.be.false;
  				} );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 0, 0 ] ),
  						2,
  						new Position( root, [ 2 ] ),
  						doc.version
  					)
  				);
  
  				const range = selection.getFirstRange();
  
  				expect( range.start.path ).to.deep.equal( [ 0, 0 ] );
  				expect( range.end.path ).to.deep.equal( [ 1, 4 ] );
  				expect( spyRange.calledOnce ).to.be.true;
  			} );
  
  			it( 'moved into before a selection', () => {
  				selection.on( 'change:range', ( evt, data ) => {
  					expect( data.directChange ).to.be.false;
  				} );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 2 ] ),
  						2,
  						new Position( root, [ 0, 0 ] ),
  						doc.version
  					)
  				);
  
  				const range = selection.getFirstRange();
  
  				expect( range.start.path ).to.deep.equal( [ 0, 4 ] );
  				expect( range.end.path ).to.deep.equal( [ 1, 4 ] );
  				expect( spyRange.calledOnce ).to.be.true;
  			} );
  
  			it( 'move range from inside of selection', () => {
  				selection.on( 'change:range', ( evt, data ) => {
  					expect( data.directChange ).to.be.false;
  				} );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 1, 0 ] ),
  						2,
  						new Position( root, [ 2 ] ),
  						doc.version
  					)
  				);
  
  				const range = selection.getFirstRange();
  
  				expect( range.start.path ).to.deep.equal( [ 0, 2 ] );
  				expect( range.end.path ).to.deep.equal( [ 1, 2 ] );
  				expect( spyRange.calledOnce ).to.be.true;
  			} );
  
  			it( 'moved range intersects with selection', () => {
  				selection.on( 'change:range', ( evt, data ) => {
  					expect( data.directChange ).to.be.false;
  				} );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 1, 3 ] ),
  						2,
  						new Position( root, [ 4 ] ),
  						doc.version
  					)
  				);
  
  				const range = selection.getFirstRange();
  
  				expect( range.start.path ).to.deep.equal( [ 0, 2 ] );
  				expect( range.end.path ).to.deep.equal( [ 1, 3 ] );
  				expect( spyRange.calledOnce ).to.be.true;
  			} );
  
  			it( 'split inside selection (do not break selection)', () => {
  				selection.on( 'change:range', ( evt, data ) => {
  					expect( data.directChange ).to.be.false;
  				} );
  
  				const batch = new Batch();
  				const splitPosition = new Position( root, [ 1, 2 ] );
  				const insertionPosition = SplitOperation.getInsertionPosition( splitPosition );
  
  				const splitOperation = new SplitOperation( splitPosition, 4, insertionPosition, null, 0 );
  
  				batch.addOperation( splitOperation );
  				model.applyOperation( splitOperation );
  
  				const range = selection.getFirstRange();
  
  				expect( range.start.path ).to.deep.equal( [ 0, 2 ] );
  				expect( range.end.path ).to.deep.equal( [ 2, 2 ] );
  				expect( spyRange.calledOnce ).to.be.true;
  			} );
  		} );
  
  		describe( 'AttributeOperation', () => {
  			it( 'changed range includes selection anchor', () => {
  				const spyAttribute = sinon.spy();
  				selection.on( 'change:attribute', spyAttribute );
  
  				selection.on( 'change:attribute', ( evt, data ) => {
  					expect( data.directChange ).to.be.false;
  					expect( data.attributeKeys ).to.deep.equal( [ 'foo' ] );
  				} );
  
  				model.applyOperation(
  					new AttributeOperation(
  						new Range( new Position( root, [ 0, 1 ] ), new Position( root, [ 0, 5 ] ) ),
  						'foo',
  						null,
  						'bar',
  						doc.version
  					)
  				);
  
  				// Attributes are auto updated on document change.
  				model.change( () => {} );
  
  				expect( selection.getAttribute( 'foo' ) ).to.equal( 'bar' );
  				expect( spyAttribute.calledOnce ).to.be.true;
  			} );
  
  			it( 'should not overwrite previously set attributes', () => {
  				selection._setAttribute( 'foo', 'xyz' );
  
  				const spyAttribute = sinon.spy();
  				selection.on( 'change:attribute', spyAttribute );
  
  				model.applyOperation(
  					new AttributeOperation(
  						new Range( new Position( root, [ 0, 1 ] ), new Position( root, [ 0, 5 ] ) ),
  						'foo',
  						null,
  						'bar',
  						doc.version
  					)
  				);
  
  				expect( selection.getAttribute( 'foo' ) ).to.equal( 'xyz' );
  				expect( spyAttribute.called ).to.be.false;
  			} );
  
  			it( 'should not overwrite previously set attributes with same values', () => {
  				selection._setAttribute( 'foo', 'xyz' );
  
  				const spyAttribute = sinon.spy();
  				selection.on( 'change:attribute', spyAttribute );
  
  				model.applyOperation(
  					new AttributeOperation(
  						new Range( new Position( root, [ 0, 1 ] ), new Position( root, [ 0, 5 ] ) ),
  						'foo',
  						null,
  						'xyz',
  						doc.version
  					)
  				);
  
  				expect( selection.getAttribute( 'foo' ) ).to.equal( 'xyz' );
  				expect( spyAttribute.called ).to.be.false;
  			} );
  
  			it( 'should not overwrite previously removed attributes', () => {
  				selection._setAttribute( 'foo', 'xyz' );
  				selection._removeAttribute( 'foo' );
  
  				const spyAttribute = sinon.spy();
  				selection.on( 'change:attribute', spyAttribute );
  
  				model.applyOperation(
  					new AttributeOperation(
  						new Range( new Position( root, [ 0, 1 ] ), new Position( root, [ 0, 5 ] ) ),
  						'foo',
  						null,
  						'bar',
  						doc.version
  					)
  				);
  
  				expect( selection.hasAttribute( 'foo' ) ).to.be.false;
  				expect( spyAttribute.called ).to.be.false;
  			} );
  		} );
  
  		describe( 'MoveOperation to graveyard', () => {
  			it( 'fix selection range if it ends up in graveyard - collapsed selection', () => {
  				selection._setTo( new Position( root, [ 1, 3 ] ) );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 1, 2 ] ),
  						2,
  						new Position( doc.graveyard, [ 0 ] ),
  						doc.version
  					)
  				);
  
  				expect( selection.getFirstPosition().path ).to.deep.equal( [ 1, 2 ] );
  			} );
  
  			it( 'fix selection range if it ends up in graveyard - text from non-collapsed selection is moved', () => {
  				selection._setTo( [ new Range( new Position( root, [ 1, 2 ] ), new Position( root, [ 1, 4 ] ) ) ] );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 1, 2 ] ),
  						2,
  						new Position( doc.graveyard, [ 0 ] ),
  						doc.version
  					)
  				);
  
  				expect( selection.getFirstPosition().path ).to.deep.equal( [ 1, 2 ] );
  			} );
  
  			it( 'fix selection range if it ends up in graveyard - parent of non-collapsed selection is moved', () => {
  				selection._setTo( [ new Range( new Position( root, [ 1, 1 ] ), new Position( root, [ 1, 2 ] ) ) ] );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 1 ] ),
  						2,
  						new Position( doc.graveyard, [ 0 ] ),
  						doc.version
  					)
  				);
  
  				expect( selection.getFirstPosition().path ).to.deep.equal( [ 0, 6 ] );
  			} );
  
  			it( 'fix selection range if it ends up in graveyard - whole content removed', () => {
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 0 ] ),
  						3,
  						new Position( doc.graveyard, [ 0 ] ),
  						doc.version
  					)
  				);
  
  				expect( selection.getFirstPosition().path ).to.deep.equal( [ 0 ] );
  
  				model.applyOperation(
  					new InsertOperation(
  						new Position( root, [ 0 ] ),
  						new Element( 'p' ),
  						doc.version
  					)
  				);
  
  				// Now it's clear that it's the default range.
  				expect( selection.getFirstPosition().path ).to.deep.equal( [ 0, 0 ] );
  			} );
  
  			it( 'handles multi-range selection in a text node by merging it into one range (resulting in a collapsed range)', () => {
  				const ranges = [
  					new Range( new Position( root, [ 1, 1 ] ), new Position( root, [ 1, 2 ] ) ),
  					new Range( new Position( root, [ 1, 3 ] ), new Position( root, [ 1, 4 ] ) )
  				];
  
  				selection._setTo( ranges );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 1, 0 ] ),
  						5,
  						new Position( doc.graveyard, [ 0 ] ),
  						doc.version
  					)
  				);
  
  				expect( selection.rangeCount ).to.equal( 1 );
  				expect( selection.getFirstPosition().path ).to.deep.equal( [ 1, 0 ] );
  				expect( selection.getLastPosition().path ).to.deep.equal( [ 1, 0 ] );
  			} );
  
  			it( 'handles multi-range selection on object nodes by merging it into one range (resulting in a non-collapsed range)', () => {
  				model.schema.register( 'outer', {
  					isObject: true
  				} );
  				model.schema.register( 'inner', {
  					isObject: true,
  					allowIn: 'outer'
  				} );
  
  				root._removeChildren( 0, root.childCount );
  				root._insertChild( 0, [
  					new Element( 'outer', [], [ new Element( 'inner' ), new Element( 'inner' ), new Element( 'inner' ) ] )
  				] );
  
  				const ranges = [
  					new Range( new Position( root, [ 0, 0 ] ), new Position( root, [ 0, 1 ] ) ),
  					new Range( new Position( root, [ 0, 1 ] ), new Position( root, [ 0, 2 ] ) )
  				];
  
  				selection._setTo( ranges );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 0, 0 ] ),
  						2,
  						new Position( doc.graveyard, [ 0 ] ),
  						doc.version
  					)
  				);
  
  				expect( selection.rangeCount ).to.equal( 1 );
  				expect( selection.getFirstPosition().path ).to.deep.equal( [ 0, 0 ] );
  				expect( selection.getLastPosition().path ).to.deep.equal( [ 0, 1 ] );
  			} );
  
  			it( 'should not fix the selection if not all ranges were removed', () => {
  				const ranges = [
  					new Range( new Position( root, [ 1, 1 ] ), new Position( root, [ 1, 2 ] ) ),
  					new Range( new Position( root, [ 1, 3 ] ), new Position( root, [ 1, 4 ] ) )
  				];
  
  				selection._setTo( ranges );
  
  				model.applyOperation(
  					new MoveOperation(
  						new Position( root, [ 1, 1 ] ),
  						1,
  						new Position( doc.graveyard, [ 0 ] ),
  						doc.version
  					)
  				);
  
  				expect( selection.rangeCount ).to.equal( 1 );
  				expect( selection.getFirstPosition().path ).to.deep.equal( [ 1, 2 ] );
  				expect( selection.getLastPosition().path ).to.deep.equal( [ 1, 3 ] );
  			} );
  		} );
  
  		it( '`DocumentSelection#change:range` event should be fire once even if selection contains multi-ranges', () => {
  			root._removeChildren( 0, root.childCount );
  			root._insertChild( 0, [
  				new Element( 'p', [], new Text( 'abcdef' ) ),
  				new Element( 'p', [], new Text( 'foobar' ) ),
  				new Text( 'xyz #2' )
  			] );
  
  			selection._setTo( [
  				Range._createIn( root.getNodeByPath( [ 0 ] ) ),
  				Range._createIn( root.getNodeByPath( [ 1 ] ) )
  			] );
  
  			spyRange = sinon.spy();
  			selection.on( 'change:range', spyRange );
  
  			model.applyOperation(
  				new InsertOperation(
  					new Position( root, [ 0 ] ),
  					'xyz #1',
  					doc.version
  				)
  			);
  
  			expect( spyRange.calledOnce ).to.be.true;
  		} );
  	} );
  
  	it( 'should throw if one of ranges starts or ends inside surrogate pair', () => {
  		root._removeChildren( 0, root.childCount );
  		root._appendChild( '\uD83D\uDCA9' );
  
  		expectToThrowCKEditorError( () => {
  			doc.selection._setTo( new Range( Position._createAt( root, 0 ), Position._createAt( root, 1 ) ) );
  		}, /document-selection-wrong-position/, model );
  
  		expectToThrowCKEditorError( () => {
  			doc.selection._setTo( new Range( Position._createAt( root, 1 ), Position._createAt( root, 2 ) ) );
  		}, /document-selection-wrong-position/, model );
  	} );
  
  	it( 'should throw if one of ranges starts or ends between base character and combining mark', () => {
  		root._removeChildren( 0, root.childCount );
  		root._appendChild( 'foo̻̐ͩbar' );
  
  		expectToThrowCKEditorError( () => {
  			doc.selection._setTo( new Range( Position._createAt( root, 3 ), Position._createAt( root, 9 ) ) );
  		}, /document-selection-wrong-position/, model );
  
  		expectToThrowCKEditorError( () => {
  			doc.selection._setTo( new Range( Position._createAt( root, 4 ), Position._createAt( root, 9 ) ) );
  		}, /document-selection-wrong-position/, model );
  
  		expectToThrowCKEditorError( () => {
  			doc.selection._setTo( new Range( Position._createAt( root, 5 ), Position._createAt( root, 9 ) ) );
  		}, /document-selection-wrong-position/, model );
  
  		expectToThrowCKEditorError( () => {
  			doc.selection._setTo( new Range( Position._createAt( root, 1 ), Position._createAt( root, 3 ) ) );
  		}, /document-selection-wrong-position/, model );
  
  		expectToThrowCKEditorError( () => {
  			doc.selection._setTo( new Range( Position._createAt( root, 1 ), Position._createAt( root, 4 ) ) );
  		}, /document-selection-wrong-position/, model );
  
  		expectToThrowCKEditorError( () => {
  			doc.selection._setTo( new Range( Position._createAt( root, 1 ), Position._createAt( root, 5 ) ) );
  		}, /document-selection-wrong-position/, model );
  	} );
  } );
  