text: /**
  * @license Apache-2.0
  *
  * Copyright (c) 2019 The Stdlib Authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *    http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
  
  'use strict';
  
  // MODULES //
  
  var tape = require( 'tape' );
  var proxyquire = require( 'proxyquire' );
  var randu = require( '@stdlib/random/iter/randu' );
  var iterEmpty = require( '@stdlib/iter/empty' );
  var array2iterator = require( '@stdlib/array/to-iterator' );
  var iteratorSymbol = require( '@stdlib/symbol/iterator' );
  var noop = require( '@stdlib/utils/noop' );
  var iterPop = require( './../lib' );
  
  
  // FUNCTIONS //
  
  function createIterator( arr ) {
  	var len;
  	var it;
  	var i;
  
  	len = arr.length;
  	i = -1;
  
  	it = {};
  	it.next = next;
  
  	return it;
  
  	function next() {
  		var out;
  		i += 1;
  		if ( i < len ) {
  			out = {};
  			out.value = arr[ i ];
  			out.done = ( i === len-1 );
  			return out;
  		}
  		return {
  			'done': true
  		};
  	}
  }
  
  
  // TESTS //
  
  tape( 'main export is a function', function test( t ) {
  	t.ok( true, __filename );
  	t.equal( typeof iterPop, 'function', 'main export is a function' );
  	t.end();
  });
  
  tape( 'the function throws an error if provided an iterator argument which is not an iterator protocol-compliant object (no other arguments)', function test( t ) {
  	var values;
  	var i;
  
  	values = [
  		'5',
  		5,
  		NaN,
  		true,
  		false,
  		null,
  		void 0,
  		{},
  		[],
  		function noop() {}
  	];
  
  	for ( i = 0; i < values.length; i++ ) {
  		t.throws( badValue( values[i] ), TypeError, 'throws an error when provided '+values[i] );
  	}
  	t.end();
  
  	function badValue( value ) {
  		return function badValue() {
  			iterPop( value );
  		};
  	}
  });
  
  tape( 'the function throws an error if provided an iterator argument which is not an iterator protocol-compliant object (callback)', function test( t ) {
  	var values;
  	var i;
  
  	values = [
  		'5',
  		5,
  		NaN,
  		true,
  		false,
  		null,
  		void 0,
  		{},
  		[],
  		function noop() {}
  	];
  
  	for ( i = 0; i < values.length; i++ ) {
  		t.throws( badValue( values[i] ), TypeError, 'throws an error when provided '+values[i] );
  	}
  	t.end();
  
  	function badValue( value ) {
  		return function badValue() {
  			iterPop( value, noop );
  		};
  	}
  });
  
  tape( 'the function throws an error if provided an iterator argument which is not an iterator protocol-compliant object (callback+context)', function test( t ) {
  	var values;
  	var i;
  
  	values = [
  		'5',
  		5,
  		NaN,
  		true,
  		false,
  		null,
  		void 0,
  		{},
  		[],
  		function noop() {}
  	];
  
  	for ( i = 0; i < values.length; i++ ) {
  		t.throws( badValue( values[i] ), TypeError, 'throws an error when provided '+values[i] );
  	}
  	t.end();
  
  	function badValue( value ) {
  		return function badValue() {
  			iterPop( value, noop, {} );
  		};
  	}
  });
  
  tape( 'the function throws an error if provided a callback argument which is not a function', function test( t ) {
  	var values;
  	var i;
  
  	values = [
  		'5',
  		5,
  		NaN,
  		true,
  		false,
  		null,
  		void 0,
  		{},
  		[]
  	];
  
  	for ( i = 0; i < values.length; i++ ) {
  		t.throws( badValue( values[i] ), TypeError, 'throws an error when provided '+values[i] );
  	}
  	t.end();
  
  	function badValue( value ) {
  		return function badValue() {
  			iterPop( array2iterator( [ 1, 2, 3 ] ), value );
  		};
  	}
  });
  
  tape( 'the function throws an error if provided a callback argument which is not a function (this context)', function test( t ) {
  	var values;
  	var i;
  
  	values = [
  		'5',
  		5,
  		NaN,
  		true,
  		false,
  		null,
  		void 0,
  		{},
  		[]
  	];
  
  	for ( i = 0; i < values.length; i++ ) {
  		t.throws( badValue( values[i] ), TypeError, 'throws an error when provided '+values[i] );
  	}
  	t.end();
  
  	function badValue( value ) {
  		return function badValue() {
  			iterPop( array2iterator( [ 1, 2, 3 ] ), value, {} );
  		};
  	}
  });
  
  tape( 'the function returns an iterator protocol-compliant object (infinite iterator)', function test( t ) {
  	var it;
  	var v;
  	var i;
  
  	it = iterPop( randu() );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	for ( i = 0; i < 100; i++ ) {
  		v = it.next();
  		t.equal( typeof v.value, 'number', 'returns expected value' );
  		t.equal( v.done, false, 'returns expected value' );
  	}
  	t.end();
  });
  
  tape( 'the function returns an iterator protocol-compliant object (finite iterator)', function test( t ) {
  	var expected;
  	var values;
  	var actual;
  	var it;
  	var i;
  
  	values = [ 1, 2, 3, 4 ];
  	expected = [
  		{
  			'value': 1,
  			'done': false
  		},
  		{
  			'value': 2,
  			'done': false
  		},
  		{
  			'value': 3,
  			'done': false
  		},
  		{
  			'done': true
  		}
  	];
  
  	it = iterPop( array2iterator( values ) );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  	t.end();
  });
  
  tape( 'the function returns an iterator protocol-compliant object (empty iterator)', function test( t ) {
  	var expected;
  	var actual;
  	var it;
  	var i;
  
  	expected = [
  		{
  			'done': true
  		}
  	];
  
  	it = iterPop( iterEmpty() );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  	t.end();
  });
  
  tape( 'the function returns an iterator protocol-compliant object (empty iterator; callback)', function test( t ) {
  	var expected;
  	var actual;
  	var it;
  	var i;
  
  	expected = [
  		{
  			'done': true
  		}
  	];
  
  	it = iterPop( iterEmpty(), clbk );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  	t.end();
  
  	function clbk() {
  		t.fail( 'should not be invoked' );
  	}
  });
  
  tape( 'the function returns an iterator protocol-compliant object (callback)', function test( t ) {
  	var expected;
  	var values;
  	var actual;
  	var FLG;
  	var it;
  	var i;
  
  	values = [ 1, 2, 3, 4 ];
  	expected = [
  		{
  			'value': 1,
  			'done': false
  		},
  		{
  			'value': 2,
  			'done': false
  		},
  		{
  			'value': 3,
  			'done': false
  		},
  		{
  			'done': true
  		}
  	];
  
  	it = iterPop( array2iterator( values ), clbk );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  
  	t.equal( FLG, true, 'returns expected value' );
  	t.end();
  
  	function clbk( v ) {
  		FLG = true;
  		t.equal( v, values[ values.length-1 ], 'returns expected value' );
  	}
  });
  
  tape( 'the function returns an iterator protocol-compliant object (value+done)', function test( t ) {
  	var expected;
  	var values;
  	var actual;
  	var it;
  	var i;
  
  	values = [ 1, 2, 3, 4 ];
  	expected = [
  		{
  			'value': 1,
  			'done': false
  		},
  		{
  			'value': 2,
  			'done': false
  		},
  		{
  			'value': 3,
  			'done': false
  		},
  		{
  			'done': true
  		}
  	];
  
  	it = iterPop( createIterator( values ) );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  	t.end();
  });
  
  tape( 'the function returns an iterator protocol-compliant object (value+done; single element iterator)', function test( t ) {
  	var expected;
  	var values;
  	var actual;
  	var it;
  	var i;
  
  	values = [ 1 ];
  	expected = [
  		{
  			'done': true
  		}
  	];
  
  	it = iterPop( createIterator( values ) );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  	t.end();
  });
  
  tape( 'the function returns an iterator protocol-compliant object (value+done; two element iterator)', function test( t ) {
  	var expected;
  	var values;
  	var actual;
  	var it;
  	var i;
  
  	values = [ 1, 2 ];
  	expected = [
  		{
  			'value': 1,
  			'done': false
  		},
  		{
  			'done': true
  		}
  	];
  
  	it = iterPop( createIterator( values ) );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  	t.end();
  });
  
  tape( 'the function returns an iterator protocol-compliant object (value+done; callback)', function test( t ) {
  	var expected;
  	var values;
  	var actual;
  	var FLG;
  	var it;
  	var i;
  
  	values = [ 1, 2, 3, 4 ];
  	expected = [
  		{
  			'value': 1,
  			'done': false
  		},
  		{
  			'value': 2,
  			'done': false
  		},
  		{
  			'value': 3,
  			'done': false
  		},
  		{
  			'done': true
  		}
  	];
  
  	it = iterPop( createIterator( values ), clbk );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  
  	t.equal( FLG, true, 'returns expected value' );
  	t.end();
  
  	function clbk( v ) {
  		FLG = true;
  		t.equal( v, values[ values.length-1 ], 'returns expected value' );
  	}
  });
  
  tape( 'the function supports specifying the callback execution context', function test( t ) {
  	var expected;
  	var values;
  	var actual;
  	var ctx;
  	var it;
  	var i;
  
  	values = [ 1, 2, 3, 4 ];
  	expected = [
  		{
  			'value': 1,
  			'done': false
  		},
  		{
  			'value': 2,
  			'done': false
  		},
  		{
  			'value': 3,
  			'done': false
  		},
  		{
  			'done': true
  		}
  	];
  
  	ctx = {
  		'FLG': false
  	};
  	it = iterPop( array2iterator( values ), clbk, ctx );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  
  	t.equal( ctx.FLG, true, 'returns expected value' );
  	t.end();
  
  	function clbk( v ) {
  		this.FLG = true; // eslint-disable-line no-invalid-this
  		t.equal( v, values[ values.length-1 ], 'returns expected value' );
  	}
  });
  
  tape( 'the function supports specifying the callback execution context (value+done)', function test( t ) {
  	var expected;
  	var values;
  	var actual;
  	var ctx;
  	var it;
  	var i;
  
  	values = [ 1, 2, 3, 4 ];
  	expected = [
  		{
  			'value': 1,
  			'done': false
  		},
  		{
  			'value': 2,
  			'done': false
  		},
  		{
  			'value': 3,
  			'done': false
  		},
  		{
  			'done': true
  		}
  	];
  
  	ctx = {
  		'FLG': false
  	};
  	it = iterPop( createIterator( values ), clbk, ctx );
  	t.equal( it.next.length, 0, 'has zero arity' );
  
  	actual = [];
  	for ( i = 0; i < expected.length; i++ ) {
  		actual.push( it.next() );
  	}
  	t.deepEqual( actual, expected, 'returns expected values' );
  
  	t.equal( ctx.FLG, true, 'returns expected value' );
  	t.end();
  
  	function clbk( v ) {
  		this.FLG = true; // eslint-disable-line no-invalid-this
  		t.equal( v, values[ values.length-1 ], 'returns expected value' );
  	}
  });
  
  tape( 'the returned iterator has a `return` method for closing an iterator (no argument)', function test( t ) {
  	var it;
  	var r;
  
  	it = iterPop( randu() );
  
  	r = it.next();
  	t.equal( typeof r.value, 'number', 'returns a number' );
  	t.equal( r.done, false, 'returns expected value' );
  
  	r = it.next();
  	t.equal( typeof r.value, 'number', 'returns a number' );
  	t.equal( r.done, false, 'returns expected value' );
  
  	r = it.return();
  	t.equal( r.value, void 0, 'returns expected value' );
  	t.equal( r.done, true, 'returns expected value' );
  
  	r = it.next();
  	t.equal( r.value, void 0, 'returns expected value' );
  	t.equal( r.done, true, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the returned iterator has a `return` method for closing an iterator (argument)', function test( t ) {
  	var it;
  	var r;
  
  	it = iterPop( randu() );
  
  	r = it.next();
  	t.equal( typeof r.value, 'number', 'returns a number' );
  	t.equal( r.done, false, 'returns expected value' );
  
  	r = it.next();
  	t.equal( typeof r.value, 'number', 'returns a number' );
  	t.equal( r.done, false, 'returns expected value' );
  
  	r = it.return( 'finished' );
  	t.equal( r.value, 'finished', 'returns expected value' );
  	t.equal( r.done, true, 'returns expected value' );
  
  	r = it.next();
  	t.equal( r.value, void 0, 'returns expected value' );
  	t.equal( r.done, true, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'if an environment supports `Symbol.iterator` and the provided iterator is iterable, the returned iterator is iterable', function test( t ) {
  	var iterPop;
  	var opts;
  	var rand;
  	var it1;
  	var it2;
  	var i;
  
  	iterPop = proxyquire( './../lib/main.js', {
  		'@stdlib/symbol/iterator': '__ITERATOR_SYMBOL__'
  	});
  
  	opts = {
  		'seed': 12345
  	};
  	rand = randu( opts );
  	rand[ '__ITERATOR_SYMBOL__' ] = factory;
  
  	it1 = iterPop( rand );
  	t.equal( typeof it1[ '__ITERATOR_SYMBOL__' ], 'function', 'has method' );
  	t.equal( it1[ '__ITERATOR_SYMBOL__' ].length, 0, 'has zero arity' );
  
  	it2 = it1[ '__ITERATOR_SYMBOL__' ]();
  	t.equal( typeof it2, 'object', 'returns an object' );
  	t.equal( typeof it2.next, 'function', 'has method' );
  	t.equal( typeof it2.return, 'function', 'has method' );
  
  	for ( i = 0; i < 100; i++ ) {
  		t.equal( it2.next().value, it1.next().value, 'returns expected value' );
  	}
  	t.end();
  
  	function factory() {
  		return randu( opts );
  	}
  });
  
  tape( 'if an environment does not support `Symbol.iterator`, the returned iterator is not "iterable"', function test( t ) {
  	var iterPop;
  	var it;
  
  	iterPop = proxyquire( './../lib/main.js', {
  		'@stdlib/symbol/iterator': false
  	});
  
  	it = iterPop( randu() );
  	t.equal( it[ iteratorSymbol ], void 0, 'does not have property' );
  
  	t.end();
  });
  
  tape( 'if a provided iterator is not iterable, the returned iterator is not iterable', function test( t ) {
  	var iterPop;
  	var rand;
  	var it;
  
  	iterPop = proxyquire( './../lib/main.js', {
  		'@stdlib/symbol/iterator': '__ITERATOR_SYMBOL__'
  	});
  
  	rand = randu();
  	rand[ '__ITERATOR_SYMBOL__' ] = null;
  
  	it = iterPop( rand );
  	t.equal( it[ iteratorSymbol ], void 0, 'does not have property' );
  
  	t.end();
  });
  