text: /**
   * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
   * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
   */
  
  import Model from '../../src/model/model';
  import ModelRange from '../../src/model/range';
  import ViewRange from '../../src/view/range';
  import DataController from '../../src/controller/datacontroller';
  import HtmlDataProcessor from '../../src/dataprocessor/htmldataprocessor';
  
  import ModelDocumentFragment from '../../src/model/documentfragment';
  import ViewDocumentFragment from '../../src/view/documentfragment';
  import ViewDocument from '../../src/view/document';
  
  import { getData, setData, stringify, parse as parseModel } from '../../src/dev-utils/model';
  import { parse as parseView, stringify as stringifyView } from '../../src/dev-utils/view';
  
  import count from '@ckeditor/ckeditor5-utils/src/count';
  
  import UpcastHelpers from '../../src/conversion/upcasthelpers';
  import DowncastHelpers from '../../src/conversion/downcasthelpers';
  import { expectToThrowCKEditorError } from '@ckeditor/ckeditor5-utils/tests/_utils/utils';
  import { StylesProcessor } from '../../src/view/stylesmap';
  
  describe( 'DataController', () => {
  	let model, modelDocument, htmlDataProcessor, data, schema, upcastHelpers, downcastHelpers, viewDocument;
  
  	beforeEach( () => {
  		const stylesProcessor = new StylesProcessor();
  		model = new Model();
  
  		schema = model.schema;
  		modelDocument = model.document;
  
  		modelDocument.createRoot();
  		modelDocument.createRoot( '$title', 'title' );
  
  		schema.register( '$title', { inheritAllFrom: '$root' } );
  
  		viewDocument = new ViewDocument( stylesProcessor );
  		htmlDataProcessor = new HtmlDataProcessor( viewDocument );
  
  		data = new DataController( model, stylesProcessor );
  		data.processor = htmlDataProcessor;
  
  		upcastHelpers = new UpcastHelpers( [ data.upcastDispatcher ] );
  		downcastHelpers = new DowncastHelpers( [ data.downcastDispatcher ] );
  	} );
  
  	describe( 'constructor()', () => {
  		it( 'sets the model and styles processor properties', () => {
  			const stylesProcessor = new StylesProcessor();
  			const data = new DataController( model, stylesProcessor );
  
  			expect( data.model ).to.equal( model );
  			expect( data.stylesProcessor ).to.equal( stylesProcessor );
  		} );
  
  		it( 'should create the #viewDocument property', () => {
  			const stylesProcessor = new StylesProcessor();
  			const data = new DataController( model, stylesProcessor );
  
  			expect( data.viewDocument ).to.be.instanceOf( ViewDocument );
  		} );
  	} );
  
  	describe( 'parse()', () => {
  		it( 'should set text', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			const output = data.parse( '<p>foo<b>bar</b></p>' );
  
  			expect( output ).to.instanceof( ModelDocumentFragment );
  			expect( stringify( output ) ).to.equal( 'foobar' );
  		} );
  
  		it( 'should set paragraph', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  
  			upcastHelpers.elementToElement( { view: 'p', model: 'paragraph' } );
  
  			const output = data.parse( '<p>foo<b>bar</b></p>' );
  
  			expect( output ).to.instanceof( ModelDocumentFragment );
  			expect( stringify( output ) ).to.equal( '<paragraph>foobar</paragraph>' );
  		} );
  
  		it( 'should set two paragraphs', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  
  			upcastHelpers.elementToElement( { view: 'p', model: 'paragraph' } );
  
  			const output = data.parse( '<p>foo</p><p>bar</p>' );
  
  			expect( output ).to.instanceof( ModelDocumentFragment );
  			expect( stringify( output ) ).to.equal( '<paragraph>foo</paragraph><paragraph>bar</paragraph>' );
  		} );
  
  		it( 'should set paragraphs with bold', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			schema.extend( '$text', {
  				allowAttributes: [ 'bold' ]
  			} );
  
  			upcastHelpers.elementToElement( { view: 'p', model: 'paragraph' } );
  			upcastHelpers.elementToAttribute( { view: 'strong', model: 'bold' } );
  
  			const output = data.parse( '<p>foo<strong>bar</strong></p>' );
  
  			expect( output ).to.instanceof( ModelDocumentFragment );
  			expect( stringify( output ) ).to.equal( '<paragraph>foo<$text bold="true">bar</$text></paragraph>' );
  		} );
  
  		it( 'should parse in the root context by default', () => {
  			const output = data.parse( 'foo' );
  
  			expect( stringify( output ) ).to.equal( '' );
  		} );
  
  		it( 'should accept parsing context', () => {
  			const output = data.parse( 'foo', [ '$block' ] );
  
  			expect( stringify( output ) ).to.equal( 'foo' );
  		} );
  	} );
  
  	describe( 'toModel()', () => {
  		beforeEach( () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  
  			upcastHelpers.elementToElement( { view: 'p', model: 'paragraph' } );
  		} );
  
  		it( 'should convert content of an element #1', () => {
  			const viewElement = parseView( '<p>foo</p>' );
  			const output = data.toModel( viewElement );
  
  			expect( output ).to.instanceof( ModelDocumentFragment );
  			expect( stringify( output ) ).to.equal( '<paragraph>foo</paragraph>' );
  		} );
  
  		it( 'should convert content of an element #2', () => {
  			const viewFragment = parseView( '<p>foo</p><p>bar</p>' );
  			const output = data.toModel( viewFragment );
  
  			expect( output ).to.be.instanceOf( ModelDocumentFragment );
  			expect( stringify( output ) ).to.equal( '<paragraph>foo</paragraph><paragraph>bar</paragraph>' );
  		} );
  
  		it( 'should accept parsing context', () => {
  			modelDocument.createRoot( 'inlineRoot', 'inlineRoot' );
  
  			schema.register( 'inlineRoot' );
  			schema.extend( '$text', { allowIn: 'inlineRoot' } );
  
  			const viewFragment = new ViewDocumentFragment( viewDocument, [ parseView( 'foo' ) ] );
  
  			// Model fragment in root (note that it is auto-paragraphed because $text is not allowed directly in $root).
  			expect( stringify( data.toModel( viewFragment ) ) ).to.equal( '<paragraph>foo</paragraph>' );
  
  			// Model fragment in inline root.
  			expect( stringify( data.toModel( viewFragment, [ 'inlineRoot' ] ) ) ).to.equal( 'foo' );
  		} );
  	} );
  
  	describe( 'init()', () => {
  		it( 'should be decorated', () => {
  			const spy = sinon.spy();
  
  			data.on( 'init', spy );
  
  			data.init( 'foo bar' );
  
  			sinon.assert.calledWithExactly( spy, sinon.match.any, [ 'foo bar' ] );
  		} );
  
  		it( 'should fire ready event after init', () => {
  			const spy = sinon.spy();
  
  			data.on( 'ready', spy );
  
  			data.init( 'foo bar' );
  
  			sinon.assert.called( spy );
  		} );
  
  		it( 'should throw an error when document data is already initialized', () => {
  			data.init( '<p>Foo</p>' );
  
  			expectToThrowCKEditorError( () => {
  				data.init( '<p>Bar</p>' );
  			}, /datacontroller-init-document-not-empty/, model );
  		} );
  
  		it( 'should set data to default main root', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			data.init( 'foo' );
  
  			expect( getData( model, { withoutSelection: true } ) ).to.equal( 'foo' );
  		} );
  
  		it( 'should set data to multiple roots at once', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			data.init( { main: 'bar', title: 'baz' } );
  
  			expect( getData( model, { withoutSelection: true } ) ).to.equal( 'bar' );
  			expect( getData( model, { withoutSelection: true, rootName: 'title' } ) ).to.equal( 'baz' );
  		} );
  
  		it( 'should get root name as a parameter', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			data.init( { title: 'foo' } );
  
  			expect( getData( model, { withoutSelection: true, rootName: 'title' } ) ).to.equal( 'foo' );
  		} );
  
  		it( 'should create a batch', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			data.init( 'foo' );
  
  			expect( count( modelDocument.history.getOperations() ) ).to.equal( 1 );
  		} );
  
  		it( 'should cause firing change event', () => {
  			const spy = sinon.spy();
  
  			schema.extend( '$text', { allowIn: '$root' } );
  			model.document.on( 'change', spy );
  
  			data.init( 'foo' );
  
  			expect( spy.calledOnce ).to.be.true;
  		} );
  
  		it( 'should return a resolved Promise', () => {
  			const promise = data.init( '<p>Foo</p>' );
  
  			expect( promise ).to.be.instanceof( Promise );
  
  			return promise;
  		} );
  
  		it( 'should throw an error when non-existent root is used (single)', () => {
  			expectToThrowCKEditorError( () => {
  				data.init( { nonexistent: '<p>Bar</p>' } );
  			}, 'datacontroller-init-non-existent-root' );
  		} );
  
  		it( 'should throw an error when non-existent root is used (one of many)', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  
  			expectToThrowCKEditorError( () => {
  				data.init( { main: 'bar', nonexistent: '<p>Bar</p>' } );
  			}, /^datacontroller-init-non-existent-root/, model );
  
  			expect( getData( model, { withoutSelection: true } ) ).to.equal( '' );
  		} );
  	} );
  
  	describe( 'set()', () => {
  		it( 'should be decorated', () => {
  			const spy = sinon.spy();
  
  			data.on( 'set', spy );
  
  			data.set( 'foo bar' );
  
  			sinon.assert.calledWithExactly( spy, sinon.match.any, [ 'foo bar' ] );
  		} );
  
  		it( 'should set data to default main root', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			data.set( 'foo' );
  
  			expect( getData( model, { withoutSelection: true } ) ).to.equal( 'foo' );
  		} );
  
  		it( 'should create a batch', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			data.set( 'foo' );
  
  			expect( count( modelDocument.history.getOperations() ) ).to.equal( 1 );
  		} );
  
  		it( 'should cause firing change event', () => {
  			const spy = sinon.spy();
  
  			schema.extend( '$text', { allowIn: '$root' } );
  			model.document.on( 'change', spy );
  
  			data.set( 'foo' );
  
  			expect( spy.calledOnce ).to.be.true;
  		} );
  
  		it( 'should get root name as a parameter', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			data.set( 'foo' );
  			data.set( { title: 'Bar' } );
  
  			expect( getData( model, { withoutSelection: true, rootName: 'main' } ) ).to.equal( 'foo' );
  			expect( getData( model, { withoutSelection: true, rootName: 'title' } ) ).to.equal( 'Bar' );
  
  			expect( count( modelDocument.history.getOperations() ) ).to.equal( 2 );
  		} );
  
  		it( 'should parse given data before set in a context of correct root', () => {
  			schema.extend( '$text', { allowIn: '$title', disallowIn: '$root' } );
  			data.set( 'foo', 'main' );
  			data.set( { title: 'Bar' } );
  
  			expect( getData( model, { withoutSelection: true, rootName: 'main' } ) ).to.equal( '' );
  			expect( getData( model, { withoutSelection: true, rootName: 'title' } ) ).to.equal( 'Bar' );
  
  			expect( count( modelDocument.history.getOperations() ) ).to.equal( 2 );
  		} );
  
  		// This case was added when order of params was different and it really didn't work. Let's keep it
  		// if anyone will ever try to change this.
  		it( 'should allow setting empty data', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  
  			data.set( { title: 'foo' } );
  
  			expect( getData( model, { withoutSelection: true, rootName: 'title' } ) ).to.equal( 'foo' );
  
  			data.set( { title: '' } );
  
  			expect( getData( model, { withoutSelection: true, rootName: 'title' } ) ).to.equal( '' );
  		} );
  
  		it( 'should throw an error when non-existent root is used (single)', () => {
  			expectToThrowCKEditorError( () => {
  				data.set( { nonexistent: '<p>Bar</p>' } );
  			}, /datacontroller-set-non-existent-root/, model );
  		} );
  
  		it( 'should throw an error when non-existent root is used (one of many) without touching any roots data', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			data.set( 'foo' );
  
  			expectToThrowCKEditorError( () => {
  				data.set( { main: 'bar', nonexistent: '<p>Bar</p>' } );
  			}, /datacontroller-set-non-existent-root/, model );
  
  			expect( getData( model, { withoutSelection: true } ) ).to.equal( 'foo' );
  		} );
  
  		// https://github.com/ckeditor/ckeditor5-engine/issues/1721.
  		it( 'should not throw when setting the data with markers that already exist in the editor', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  
  			data.set( 'foo' );
  
  			downcastHelpers.markerToData( { model: 'marker' } );
  			upcastHelpers.dataToMarker( { view: 'marker' } );
  
  			model.change( writer => {
  				writer.addMarker( 'marker', { range: writer.createRangeIn( modelDocument.getRoot() ), usingOperation: true } );
  			} );
  
  			expect( () => {
  				data.set( data.get() );
  			} ).not.to.throw();
  		} );
  	} );
  
  	describe( 'get()', () => {
  		it( 'should get paragraph with text', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			setData( model, '<paragraph>foo</paragraph>' );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  
  			expect( data.get() ).to.equal( '<p>foo</p>' );
  			expect( data.get( { trim: 'empty' } ) ).to.equal( '<p>foo</p>' );
  		} );
  
  		it( 'should trim empty paragraph by default', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			setData( model, '<paragraph></paragraph>' );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  
  			expect( data.get() ).to.equal( '' );
  			expect( data.get( { trim: 'empty' } ) ).to.equal( '' );
  		} );
  
  		it( 'should get empty paragraph (with trim=none)', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			setData( model, '<paragraph></paragraph>' );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  
  			expect( data.get( { trim: 'none' } ) ).to.equal( '<p>&nbsp;</p>' );
  		} );
  
  		it( 'should get two paragraphs', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			setData( model, '<paragraph>foo</paragraph><paragraph>bar</paragraph>' );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  
  			expect( data.get() ).to.equal( '<p>foo</p><p>bar</p>' );
  			expect( data.get( { trim: 'empty' } ) ).to.equal( '<p>foo</p><p>bar</p>' );
  		} );
  
  		it( 'should get text directly in root', () => {
  			schema.extend( '$text', { allowIn: '$root' } );
  			setData( model, 'foo' );
  
  			expect( data.get() ).to.equal( 'foo' );
  			expect( data.get( { trim: 'empty' } ) ).to.equal( 'foo' );
  		} );
  
  		it( 'should get paragraphs without bold', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			setData( model, '<paragraph>foo<$text bold="true">bar</$text></paragraph>' );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  
  			expect( data.get() ).to.equal( '<p>foobar</p>' );
  			expect( data.get( { trim: 'empty' } ) ).to.equal( '<p>foobar</p>' );
  		} );
  
  		it( 'should get paragraphs with bold', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			setData( model, '<paragraph>foo<$text bold="true">bar</$text></paragraph>' );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  			downcastHelpers.attributeToElement( { model: 'bold', view: 'strong' } );
  
  			expect( data.get() ).to.equal( '<p>foo<strong>bar</strong></p>' );
  			expect( data.get( { trim: 'empty' } ) ).to.equal( '<p>foo<strong>bar</strong></p>' );
  		} );
  
  		it( 'should get root name as a parameter', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			schema.extend( '$text', { allowIn: '$root' } );
  
  			setData( model, '<paragraph>foo</paragraph>', { rootName: 'main' } );
  			setData( model, 'Bar', { rootName: 'title' } );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  			downcastHelpers.attributeToElement( { model: 'bold', view: 'strong' } );
  
  			expect( data.get() ).to.equal( '<p>foo</p>' );
  			expect( data.get( { rootName: 'main' } ) ).to.equal( '<p>foo</p>' );
  			expect( data.get( { rootName: 'title' } ) ).to.equal( 'Bar' );
  		} );
  
  		it( 'should throw an error when non-existent root is used', () => {
  			expectToThrowCKEditorError( () => {
  				data.get( { rootName: 'nonexistent' } );
  			}, 'datacontroller-get-non-existent-root' );
  		} );
  
  		it( 'should allow to provide additional options for retrieving data - insert conversion', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  
  			data.downcastDispatcher.on( 'insert:paragraph', ( evt, data, conversionApi ) => {
  				conversionApi.consumable.consume( data.item, 'insert' );
  
  				const viewPosition = conversionApi.mapper.toViewPosition( data.range.start );
  				const viewElement = conversionApi.writer.createContainerElement( 'p', {
  					attribute: conversionApi.options.attributeValue
  				} );
  
  				conversionApi.mapper.bindElements( data.item, viewElement );
  				conversionApi.writer.insert( viewPosition, viewElement );
  			}, { priority: 'high' } );
  
  			setData( model, '<paragraph>foo</paragraph>' );
  
  			expect( data.get( { attributeValue: 'foo' } ) ).to.equal( '<p attribute="foo">foo</p>' );
  			expect( data.get( { attributeValue: 'bar' } ) ).to.equal( '<p attribute="bar">foo</p>' );
  		} );
  
  		it( 'should allow to provide additional options for retrieving data - attribute conversion', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block', allowAttributes: [ 'foo' ] } );
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  
  			data.downcastDispatcher.on( 'attribute:foo', ( evt, data, conversionApi ) => {
  				if ( data.attributeNewValue === conversionApi.options.skipAttribute ) {
  					return;
  				}
  
  				const viewRange = conversionApi.mapper.toViewRange( data.range );
  				const viewElement = conversionApi.writer.createAttributeElement( data.attributeNewValue );
  
  				conversionApi.writer.wrap( viewRange, viewElement );
  			} );
  
  			setData( model, '<paragraph>f<$text foo="a">o</$text>ob<$text foo="b">a</$text>r</paragraph>' );
  
  			expect( data.get() ).to.equal( '<p>f<a>o</a>ob<b>a</b>r</p>' );
  			expect( data.get( { skipAttribute: 'a' } ) ).to.equal( '<p>foob<b>a</b>r</p>' );
  			expect( data.get( { skipAttribute: 'b' } ) ).to.equal( '<p>f<a>o</a>obar</p>' );
  		} );
  
  		it( 'should allow to provide additional options for retrieving data - addMarker conversion', () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  
  			data.downcastDispatcher.on( 'addMarker', ( evt, data, conversionApi ) => {
  				if ( conversionApi.options.skipMarker ) {
  					return;
  				}
  
  				const viewElement = conversionApi.writer.createAttributeElement( 'marker' );
  				const viewRange = conversionApi.mapper.toViewRange( data.markerRange );
  
  				conversionApi.writer.wrap( viewRange, viewElement );
  			} );
  
  			setData( model, '<paragraph>foo</paragraph>' );
  
  			const root = model.document.getRoot();
  
  			model.change( writer => {
  				const start = writer.createPositionFromPath( root, [ 0, 1 ] );
  				const end = writer.createPositionFromPath( root, [ 0, 2 ] );
  
  				writer.addMarker( 'marker', {
  					range: writer.createRange( start, end ),
  					usingOperation: false
  				} );
  			} );
  
  			expect( data.get( { skipMarker: false } ) ).to.equal( '<p>f<marker>o</marker>o</p>' );
  			expect( data.get( { skipMarker: true } ) ).to.equal( '<p>foo</p>' );
  		} );
  	} );
  
  	describe( 'stringify()', () => {
  		beforeEach( () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			schema.register( 'div' );
  
  			schema.extend( '$block', { allowIn: 'div' } );
  			schema.extend( 'div', { allowIn: '$root' } );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  		} );
  
  		it( 'should stringify a content of an element', () => {
  			const modelElement = parseModel( '<div><paragraph>foo</paragraph></div>', schema );
  
  			expect( data.stringify( modelElement ) ).to.equal( '<p>foo</p>' );
  		} );
  
  		it( 'should stringify a content of a document fragment', () => {
  			const modelDocumentFragment = parseModel( '<paragraph>foo</paragraph><paragraph>bar</paragraph>', schema );
  
  			expect( data.stringify( modelDocumentFragment ) ).to.equal( '<p>foo</p><p>bar</p>' );
  		} );
  
  		it( 'should allow to provide additional options to the conversion process', () => {
  			const spy = sinon.spy();
  
  			data.downcastDispatcher.on( 'insert:paragraph', ( evt, data, conversionApi ) => {
  				spy( conversionApi.options );
  			}, { priority: 'high' } );
  
  			const modelDocumentFragment = parseModel( '<paragraph>foo</paragraph><paragraph>bar</paragraph>', schema );
  
  			const options = { foo: 'bar' };
  
  			data.stringify( modelDocumentFragment );
  			expect( spy.lastCall.args[ 0 ] ).to.not.equal( options );
  
  			data.stringify( modelDocumentFragment, options );
  			expect( spy.lastCall.args[ 0 ] ).to.equal( options );
  		} );
  	} );
  
  	describe( 'toView()', () => {
  		beforeEach( () => {
  			schema.register( 'paragraph', { inheritAllFrom: '$block' } );
  			schema.register( 'div' );
  
  			schema.extend( '$block', { allowIn: 'div' } );
  			schema.extend( 'div', { allowIn: '$root' } );
  
  			downcastHelpers.elementToElement( { model: 'paragraph', view: 'p' } );
  		} );
  
  		it( 'should use #viewDocument as a parent for returned document fragments', () => {
  			const modelElement = parseModel( '<div><paragraph>foo</paragraph></div>', schema );
  			const viewDocumentFragment = data.toView( modelElement );
  
  			expect( viewDocumentFragment.document ).to.equal( data.viewDocument );
  		} );
  
  		it( 'should convert a content of an element', () => {
  			const modelElement = parseModel( '<div><paragraph>foo</paragraph></div>', schema );
  
  			const viewDocumentFragment = data.toView( modelElement );
  
  			expect( viewDocumentFragment ).to.be.instanceOf( ViewDocumentFragment );
  
  			const viewElement = viewDocumentFragment.getChild( 0 );
  
  			expect( viewElement.name ).to.equal( 'p' );
  			expect( viewElement.childCount ).to.equal( 1 );
  			expect( viewElement.getChild( 0 ).data ).to.equal( 'foo' );
  		} );
  
  		it( 'should correctly convert document markers #1', () => {
  			const modelElement = parseModel( '<div><paragraph>foobar</paragraph></div>', schema );
  			const modelRoot = model.document.getRoot();
  
  			downcastHelpers.markerToHighlight( { model: 'marker:a', view: { classes: 'a' } } );
  
  			model.change( writer => {
  				writer.insert( modelElement, modelRoot, 0 );
  				const range = writer.createRange( writer.createPositionAt( modelRoot, 0 ), writer.createPositionAt( modelRoot, 1 ) );
  				writer.addMarker( 'marker:a', { range, usingOperation: true } );
  			} );
  
  			const viewDocumentFragment = data.toView( modelElement );
  			const viewElement = viewDocumentFragment.getChild( 0 );
  
  			expect( stringifyView( viewElement ) ).to.equal( '<p><span class="a">foobar</span></p>' );
  		} );
  
  		it( 'should correctly convert document markers #2', () => {
  			const modelElement = parseModel( '<div><paragraph>foo</paragraph><paragraph>bar</paragraph></div>', schema );
  			const modelRoot = model.document.getRoot();
  
  			downcastHelpers.markerToHighlight( { model: 'marker:a', view: { classes: 'a' } } );
  			downcastHelpers.markerToHighlight( { model: 'marker:b', view: { classes: 'b' } } );
  
  			const modelP1 = modelElement.getChild( 0 );
  			const modelP2 = modelElement.getChild( 1 );
  
  			model.change( writer => {
  				writer.insert( modelElement, modelRoot, 0 );
  
  				const rangeA = writer.createRange( writer.createPositionAt( modelP1, 1 ), writer.createPositionAt( modelP1, 3 ) );
  				const rangeB = writer.createRange( writer.createPositionAt( modelP2, 0 ), writer.createPositionAt( modelP2, 2 ) );
  
  				writer.addMarker( 'marker:a', { range: rangeA, usingOperation: true } );
  				writer.addMarker( 'marker:b', { range: rangeB, usingOperation: true } );
  			} );
  
  			const viewDocumentFragment = data.toView( modelP1 );
  
  			expect( stringifyView( viewDocumentFragment ) ).to.equal( 'f<span class="a">oo</span>' );
  		} );
  
  		it( 'should convert a document fragment', () => {
  			const modelDocumentFragment = parseModel( '<paragraph>foo</paragraph><paragraph>bar</paragraph>', schema );
  			const viewDocumentFragment = data.toView( modelDocumentFragment );
  
  			expect( viewDocumentFragment ).to.be.instanceOf( ViewDocumentFragment );
  			expect( viewDocumentFragment ).to.have.property( 'childCount', 2 );
  
  			const viewElement = viewDocumentFragment.getChild( 0 );
  
  			expect( viewElement.name ).to.equal( 'p' );
  			expect( viewElement.childCount ).to.equal( 1 );
  			expect( viewElement.getChild( 0 ).data ).to.equal( 'foo' );
  		} );
  
  		it( 'should keep view-model mapping', () => {
  			const modelDocumentFragment = parseModel( '<paragraph>foo</paragraph><paragraph>bar</paragraph>', schema );
  			const viewDocumentFragment = data.toView( modelDocumentFragment );
  
  			const firstModelElement = modelDocumentFragment.getChild( 0 );
  			const firstViewElement = viewDocumentFragment.getChild( 0 );
  
  			const modelRange = ModelRange._createOn( firstModelElement );
  			const viewRange = ViewRange._createOn( firstViewElement );
  
  			const mappedModelRange = data.mapper.toModelRange( viewRange );
  			const mappedViewRange = data.mapper.toViewRange( modelRange );
  
  			expect( mappedModelRange ).to.be.instanceOf( ModelRange );
  			expect( mappedViewRange ).to.be.instanceOf( ViewRange );
  
  			expect( mappedModelRange.end.nodeBefore ).to.equal( firstModelElement );
  			expect( mappedModelRange.end.nodeAfter ).to.equal( modelDocumentFragment.getChild( 1 ) );
  			expect( mappedViewRange.end.nodeBefore ).to.equal( firstViewElement );
  			expect( mappedViewRange.end.nodeAfter ).to.equal( viewDocumentFragment.getChild( 1 ) );
  		} );
  
  		it( 'should allow to provide additional options to the conversion process', () => {
  			const root = model.document.getRoot();
  			const spy = sinon.spy();
  
  			data.downcastDispatcher.on( 'insert:paragraph', ( evt, data, conversionApi ) => {
  				spy( conversionApi.options );
  			}, { priority: 'high' } );
  
  			data.downcastDispatcher.on( 'addMarker:marker', ( evt, data, conversionApi ) => {
  				spy( conversionApi.options );
  			}, { priority: 'high' } );
  
  			setData( model, '<paragraph>foo</paragraph>' );
  
  			model.change( writer => {
  				writer.addMarker( 'marker', {
  					range: model.createRange( model.createPositionFromPath( root, [ 0, 1 ] ) ),
  					usingOperation: false
  				} );
  			} );
  
  			const options = { foo: 'bar' };
  
  			data.toView( root, options );
  
  			sinon.assert.calledTwice( spy );
  			expect( spy.firstCall.args[ 0 ] ).to.equal( options );
  			expect( spy.lastCall.args[ 0 ] ).to.equal( options );
  		} );
  	} );
  
  	describe( 'destroy()', () => {
  		it( 'should be there for you', () => {
  			// Should not throw.
  			data.destroy();
  
  			expect( data ).to.respondTo( 'destroy' );
  		} );
  	} );
  
  	describe( 'addStyleProcessorRules()', () => {
  		it( 'should execute callback with an instance of StyleProcessor as the first argument', () => {
  			const stylesProcessor = new StylesProcessor();
  			const data = new DataController( model, stylesProcessor );
  
  			const spy = sinon.spy();
  
  			data.addStyleProcessorRules( spy );
  
  			sinon.assert.calledOnce( spy );
  			sinon.assert.calledWithExactly( spy, stylesProcessor );
  		} );
  	} );
  } );
  