test: update callback tests

Signed-off-by: Athan <[email protected]>

Author: kgryte

lib/node_modules/@stdlib/stats/array/max-by/test/test.js

@@ -202,39 +202,81 @@ tape( 'the function calculates the maximum value of an array (array-like object)
 });
 
 tape( 'the function supports providing a callback execution context', function test( t ) {
+	var expected;
+	var indices;
+	var values;
+	var arrays;
 	var ctx;
 	var x;
 
 	x = [ 1.0, 2.0, 3.0, 4.0, 5.0 ];
 	ctx = {
 		'count': 0
 	};
+	indices = [];
+	values = [];
+	arrays = [];
 	maxBy( x, accessor, ctx );
 
 	t.strictEqual( ctx.count, x.length, 'returns expected value' );
+
+	expected = [ 0, 1, 2, 3, 4 ];
+	t.deepEqual( indices, expected, 'returns expected value' );
+
+	expected = [ 1.0, 2.0, 3.0, 4.0, 5.0 ];
+	t.deepEqual( values, expected, 'returns expected value' );
+
+	expected = [ x, x, x, x, x ];
+	t.deepEqual( arrays, expected, 'returns expected value' );
+	
 	t.end();
 
-	function accessor( v ) {
+	function accessor( v, idx, arr ) {
 		this.count += 1; // eslint-disable-line no-invalid-this
+		indices.push( idx );
+		values.push( v );
+		arrays.push( arr );
 		return v * 2.0;
 	}
 });
 
 tape( 'the function supports providing a callback execution context (accessors)', function test( t ) {
+	var expected;
+	var indices;
+	var values;
+	var arrays;
 	var ctx;
+	var ax;
 	var x;
 
 	x = [ 1.0, 2.0, 3.0, 4.0, 5.0 ];
+	ax = toAccessorArray( x );
 	ctx = {
 		'count': 0
 	};
-	maxBy( toAccessorArray( x ), accessor, ctx );
+	indices = [];
+	values = [];
+	arrays = [];
+	maxBy( ax, accessor, ctx );
 
 	t.strictEqual( ctx.count, x.length, 'returns expected value' );
+
+	expected = [ 0, 1, 2, 3, 4 ];
+	t.deepEqual( indices, expected, 'returns expected value' );
+
+	expected = [ 1.0, 2.0, 3.0, 4.0, 5.0 ];
+	t.deepEqual( values, expected, 'returns expected value' );
+
+	expected = [ ax, ax, ax, ax, ax ];
+	t.deepEqual( arrays, expected, 'returns expected value' );
+	
 	t.end();
 
-	function accessor( v ) {
+	function accessor( v, idx, arr ) {
 		this.count += 1; // eslint-disable-line no-invalid-this
+		indices.push( idx );
+		values.push( v );
+		arrays.push( arr );
 		return v * 2.0;
 	}
 });