wip: code formatting nits continued

test/concat.spec.js

@@ -0,0 +1,56 @@
+import lodashStable from 'lodash';
+import concat from '../src/concat';
+
+describe('concat', () => {
+    it('should shallow clone `array`', () => {
+        const array = [1, 2, 3];
+        const actual = concat(array);
+
+        expect(actual).toEqual(array);
+        assert.notStrictEqual(actual, array);
+    });
+
+    it('should concat arrays and values', () => {
+        const array = [1];
+        const actual = concat(array, 2, [3], [[4]]);
+
+        expect(actual).toEqual([1, 2, 3, [4]]);
+        expect(array).toEqual([1]);
+    });
+
+    it('should cast non-array `array` values to arrays', () => {
+        const values = [, null, undefined, false, true, 1, NaN, 'a'];
+
+        let expected = lodashStable.map(values, (value, index) => (index ? [value] : []));
+
+        let actual = lodashStable.map(values, (value, index) => (index ? concat(value) : concat()));
+
+        expect(actual).toEqual(expected);
+
+        expected = lodashStable.map(values, (value) => [value, 2, [3]]);
+
+        actual = lodashStable.map(values, (value) => concat(value, [2], [[3]]));
+
+        expect(actual).toEqual(expected);
+    });
+
+    it('should treat sparse arrays as dense', () => {
+        const expected = [];
+        const actual = concat(Array(1), Array(1));
+
+        expected.push(undefined, undefined);
+
+        expect('0' in actual)
+        expect('1' in actual)
+        expect(actual).toEqual(expected);
+    });
+
+    it('should return a new wrapped array', () => {
+        const array = [1];
+        const wrapped = _(array).concat([2, 3]);
+        const actual = wrapped.value();
+
+        expect(array).toEqual([1]);
+        expect(actual, [1, 2).toEqual(3]);
+    });
+});