test.js

'use strict';

// MODULES //

var tape = require( 'tape' );
var noop = require( '@stdlib/utils/noop' );
var Float64Array = require( '@stdlib/array/float64' );
var groupBy = require( './../lib' );


// TESTS //

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

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

	values = [
		'5',
		5,
		NaN,
		true,
		false,
		null,
		undefined,
		{},
		function noop() {},
		/.*/,
		new Date()
	];

	for ( i = 0; i < values.length; i++ ) {
		t.throws( badValue( values[i] ), TypeError, 'throws a type error when provided '+values[i] );
	}
	t.end();

	function badValue( value ) {
		return function badValue() {
			groupBy( value, noop );
		};
	}
});

tape( 'the function throws an error if not provided an indicator function (no options)', function test( t ) {
	var values;
	var i;

	values = [
		'5',
		5,
		NaN,
		true,
		false,
		null,
		undefined,
		{},
		[],
		/.*/,
		new Date()
	];

	for ( i = 0; i < values.length; i++ ) {
		t.throws( badValue( values[i] ), TypeError, 'throws a type error when provided '+values[i] );
	}
	t.end();

	function badValue( value ) {
		return function badValue() {
			groupBy( [ 1, 2, 3 ], value );
		};
	}
});

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

	values = [
		'5',
		5,
		NaN,
		true,
		false,
		null,
		undefined,
		{},
		[],
		/.*/,
		new Date()
	];

	for ( i = 0; i < values.length; i++ ) {
		t.throws( badValue( values[i] ), TypeError, 'throws a type error when provided '+values[i] );
	}
	t.end();

	function badValue( value ) {
		return function badValue() {
			groupBy( [ 1, 2, 3 ], {}, value );
		};
	}
});

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

	values = [
		'5',
		5,
		NaN,
		true,
		false,
		null,
		undefined,
		[],
		function noop() {},
		/.*/,
		new Date()
	];

	for ( i = 0; i < values.length; i++ ) {
		t.throws( badValue( values[i] ), TypeError, 'throws a type error when provided '+values[i] );
	}
	t.end();

	function badValue( value ) {
		return function badValue() {
			groupBy( [ 1, 2, 3 ], value, noop );
		};
	}
});

tape( 'the function throws an error if provided an invalid option', function test( t ) {
	var values;
	var i;

	values = [
		'5',
		5,
		NaN,
		true,
		false,
		null,
		undefined,
		[],
		function noop() {},
		/.*/,
		new Date()
	];

	for ( i = 0; i < values.length; i++ ) {
		t.throws( badValue( values[i] ), TypeError, 'throws a type error when provided '+values[i] );
	}
	t.end();

	function badValue( value ) {
		return function badValue() {
			var opts = {
				'returns': value
			};
			groupBy( [ 1, 2, 3 ], opts, noop );
		};
	}
});

tape( 'the function groups collection elements as lists according to an indicator function', function test( t ) {
	var expected;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = [ 'beep', 'boop', 'foo', 'bar' ];

	expected = {
		'b': [ 'beep', 'boop', 'bar' ],
		'f': [ 'foo' ]
	};
	out = groupBy( arr, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'the function groups collection elements as lists according to an indicator function (values)', function test( t ) {
	var expected;
	var opts;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = [ 'beep', 'boop', 'foo', 'bar' ];

	opts = {
		'returns': 'values'
	};

	expected = {
		'b': [ 'beep', 'boop', 'bar' ],
		'f': [ 'foo' ]
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'the function groups collection elements as lists according to an indicator function (indices)', function test( t ) {
	var expected;
	var opts;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = [ 'beep', 'boop', 'foo', 'bar' ];

	opts = {
		'returns': 'indices'
	};

	expected = {
		'b': [ 0, 1, 3 ],
		'f': [ 2 ]
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'the function groups collection elements as lists according to an indicator function (pairs)', function test( t ) {
	var expected;
	var opts;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = [ 'beep', 'boop', 'foo', 'bar' ];

	opts = {
		'returns': '*'
	};

	expected = {
		'b': [ [ 0, 'beep' ], [ 1, 'boop' ], [ 3, 'bar' ] ],
		'f': [ [ 2, 'foo' ] ]
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'the function groups collection elements as lists according to an indicator function (typed array)', function test( t ) {
	var expected;
	var opts;
	var out;
	var arr;

	function indicator( v ) {
		return v;
	}

	arr = new Float64Array( [ 0, 1, 1, 0 ] );

	opts = {
		'returns': 'values'
	};

	expected = {
		'0': [ 0, 0 ],
		'1': [ 1, 1 ]
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'the function groups collection elements as lists according to an indicator function (array-like object)', function test( t ) {
	var expected;
	var opts;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = {
		'length': 4,
		'0': 'beep',
		'1': 'boop',
		'2': 'foo',
		'3': 'bar'
	};
	opts = {
		'returns': 'values'
	};

	expected = {
		'b': [ 'beep', 'boop', 'bar' ],
		'f': [ 'foo' ]
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'the function groups collection elements as lists according to an indicator function (string serialization)', function test( t ) {
	var expected;
	var out;
	var arr;

	function indicator() {
		return {};
	}

	arr = [ 'beep', 'boop', 'foo', 'bar' ];

	expected = {
		'[object Object]': [ 'beep', 'boop', 'foo', 'bar' ]
	};
	out = groupBy( arr, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'the function groups collection elements as lists according to an indicator function (string serialization)', function test( t ) {
	var expected;
	var out;
	var arr;

	function indicator() {}

	arr = [ 'beep', 'boop', 'foo', 'bar' ];

	expected = {
		'undefined': [ 'beep', 'boop', 'foo', 'bar' ]
	};
	out = groupBy( arr, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

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

	function indicator( v ) {
		return v * this.scalar; // eslint-disable-line no-invalid-this
	}

	ctx = {
		'scalar': 2
	};

	arr = [ 0, 1, 1, 0 ];

	opts = {
		'thisArg': ctx
	};
	expected = {
		'0': [ 0, 0 ],
		'2': [ 1, 1 ]
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'the function invokes the indicator function with both the collection element and the element index', function test( t ) {
	var expected;
	var out;
	var arr;

	function indicator( v, i ) {
		return v * i;
	}

	arr = [ 2, 2, 2, 2 ];

	expected = {
		'0': [ 2 ],
		'2': [ 2 ],
		'4': [ 2 ],
		'6': [ 2 ]
	};
	out = groupBy( arr, indicator );

	t.deepEqual( out, expected, 'returns expected groups' );
	t.end();
});

tape( 'if provided an empty collection, the function returns an empty object', function test( t ) {
	var expected;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = [];

	expected = {};
	out = groupBy( arr, indicator );

	t.deepEqual( out, expected, 'returns expected results' );
	t.end();
});

tape( 'if provided an empty collection, the function returns an empty object (values)', function test( t ) {
	var expected;
	var opts;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = [];
	expected = {};

	opts = {
		'returns': 'values'
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected results' );
	t.end();
});

tape( 'if provided an empty collection, the function returns an empty object (indices)', function test( t ) {
	var expected;
	var opts;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = [];
	expected = {};

	opts = {
		'returns': 'indices'
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected results' );
	t.end();
});

tape( 'if provided an empty collection, the function returns an empty object (pairs)', function test( t ) {
	var expected;
	var opts;
	var out;
	var arr;

	function indicator( v ) {
		return v[ 0 ];
	}

	arr = [];
	expected = {};

	opts = {
		'returns': '*'
	};
	out = groupBy( arr, opts, indicator );

	t.deepEqual( out, expected, 'returns expected results' );
	t.end();
});