test.js

'use strict';

// MODULES //

var tape = require( 'tape' );
var noop = require( '@stdlib/utils/noop' );
var mapFunAsync = require( './../lib' );


// TESTS //

tape( 'main export is a function', function test( t ) {
	t.ok( true, __filename );
	t.strictEqual( typeof mapFunAsync, 'function', 'main export is a function' );
	t.end();
});

tape( 'the function throws an error if provided a first argument which is not a function', function test( t ) {
	var values;
	var i;

	values = [
		'5',
		5,
		NaN,
		true,
		false,
		null,
		undefined,
		[],
		{}
	];
	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() {
			mapFunAsync( value, 10, noop );
		};
	}
});

tape( 'the function throws an error if not provided a second argument which is a nonnegative integer', function test( t ) {
	var values;
	var i;

	values = [
		'5',
		-5,
		3.14,
		NaN,
		true,
		false,
		null,
		undefined,
		[],
		{},
		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() {
			mapFunAsync( noop, value, noop );
		};
	}
});

tape( 'the function throws an error if provided an options argument which is not an object', function test( t ) {
	var values;
	var i;

	values = [
		'5',
		-5,
		3.14,
		NaN,
		true,
		false,
		null,
		undefined,
		[],
		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() {
			mapFunAsync( noop, 5, value, noop );
		};
	}
});

tape( 'the function throws an error if provided a last argument which is not a function (no options)', function test( t ) {
	var values;
	var i;

	values = [
		'5',
		5,
		NaN,
		true,
		false,
		null,
		undefined,
		[],
		{}
	];
	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() {
			mapFunAsync( noop, 10, value );
		};
	}
});

tape( 'the function throws an error if provided a last argument which is not a function (options)', function test( t ) {
	var values;
	var i;

	values = [
		'5',
		5,
		NaN,
		true,
		false,
		null,
		undefined,
		[],
		{}
	];
	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() {
			mapFunAsync( noop, 10, {}, value );
		};
	}
});

tape( 'the function invokes a function a specified number of times and returns an array of accumulated function return values', function test( t ) {
	var expected;

	expected = [ 0, 1, 2, 3, 4 ];
	mapFunAsync( fcn, 5, done );

	function fcn( i, next ) {
		setTimeout( onTimeout, 0 );
		function onTimeout() {
			next( null, i );
		}
	}

	function done( error, actual ) {
		if ( error ) {
			t.fail( error.message );
		} else {
			t.deepEqual( actual, expected, 'returns expected results' );
		}
		t.end();
	}
});

tape( 'the function invokes a function a specified number of times and returns an array of accumulated function return values (n=0)', function test( t ) {
	var expected;

	expected = [];
	mapFunAsync( fcn, 0, done );

	function fcn( i, next ) {
		setTimeout( onTimeout, 0 );
		function onTimeout() {
			next( null, i );
		}
	}

	function done( error, actual ) {
		if ( error ) {
			t.fail( error.message );
		} else {
			t.deepEqual( actual, expected, 'returns expected results' );
		}
		t.end();
	}
});

tape( 'the function supports providing an execution context for the invoked function', function test( t ) {
	var expected;
	var opts;
	var ctx;

	ctx = {
		'count': 0
	};
	opts = {
		'thisArg': ctx
	};
	expected = [ 0, 1, 2, 3, 4 ];
	mapFunAsync( fcn, 5, opts, done );

	function fcn( i, next ) {
		this.count += 1; // eslint-disable-line no-invalid-this
		setTimeout( onTimeout, 0 );
		function onTimeout() {
			next( null, i );
		}
	}

	function done( error, actual ) {
		if ( error ) {
			t.fail( error.message );
		} else {
			t.deepEqual( actual, expected, 'returns expected results' );
			t.strictEqual( ctx.count, 5, 'updates execution context' );
		}
		t.end();
	}
});

tape( 'the function returns an array containing `undefined` values if an invoked function does not return anything', function test( t ) {
	var expected;

	expected = [ void 0, void 0, void 0, void 0, void 0 ];
	mapFunAsync( fcn, 5, done );

	function fcn( i, next ) {
		setTimeout( onTimeout, 0 );
		function onTimeout() {
			next();
		}
	}

	function done( error, actual ) {
		if ( error ) {
			t.fail( error.message );
		} else {
			t.deepEqual( actual, expected, 'returns expected results' );
		}
		t.end();
	}
});

tape( 'if an error is encountered, the function suspends execution and immediately returns the error', function test( t ) {
	var count = 0;
	mapFunAsync( fcn, 500, done );

	function fcn( i, next ) {
		setTimeout( onTimeout, 0 );
		function onTimeout() {
			count += 1;
			if ( i === 2 ) {
				return next( new Error( 'beep' ) );
			}
			next( null, i );
		}
	}

	function done( error ) {
		if ( error ) {
			t.pass( error.message );
		} else {
			t.fail( 'should return an error' );
		}
		t.strictEqual( count, 3, 'suspends execution' );
		t.end();
	}
});

tape( 'the function does not guarantee asynchrony', function test( t ) {
	var expected;
	var flg;

	expected = [ 0, 1, 2, 3, 4 ];
	flg = 0;
	mapFunAsync( fcn, 5, done );
	flg = 1;

	function fcn( i, next ) {
		next( null, i );
	}

	function done( error, actual ) {
		if ( error ) {
			t.fail( error.message );
		} else {
			t.deepEqual( actual, expected, 'returns expected results' );
		}
		t.strictEqual( flg, 0, 'is not asynchronous' );
		t.end();
	}
});