Coerce to integer and set default value for chunk size parameter (#4413)

* Enable chunk module tests

* Coerce to integer and set default value for chunk size param

test/chunk.test.js

@@ -0,0 +1,45 @@
+import assert from 'assert';
+import lodashStable from 'lodash';
+import { falsey, stubArray } from './utils.js';
+import chunk from '../chunk.js';
+
+describe('chunk', function() {
+  var array = [0, 1, 2, 3, 4, 5];
+
+  it('should return chunked arrays', function() {
+    var actual = chunk(array, 3);
+    assert.deepStrictEqual(actual, [[0, 1, 2], [3, 4, 5]]);
+  });
+
+  it('should return the last chunk as remaining elements', function() {
+    var actual = chunk(array, 4);
+    assert.deepStrictEqual(actual, [[0, 1, 2, 3], [4, 5]]);
+  });
+
+  it('should treat falsey `size` values, except `undefined`, as `0`', function() {
+    var expected = lodashStable.map(falsey, function(value) {
+      return value === undefined ? [[0], [1], [2], [3], [4], [5]] : [];
+    });
+
+    var actual = lodashStable.map(falsey, function(size, index) {
+      return index ? chunk(array, size) : chunk(array);
+    });
+
+    assert.deepStrictEqual(actual, expected);
+  });
+
+  it('should ensure the minimum `size` is `0`', function() {
+    var values = lodashStable.reject(falsey, lodashStable.isUndefined).concat(-1, -Infinity),
+        expected = lodashStable.map(values, stubArray);
+
+    var actual = lodashStable.map(values, function(n) {
+      return chunk(array, n);
+    });
+
+    assert.deepStrictEqual(actual, expected);
+  });
+
+  it('should coerce `size` to an integer', function() {
+    assert.deepStrictEqual(chunk(array, array.length / 4), [[0], [1], [2], [3], [4], [5]]);
+  });
+});