tests(filter): add tests for filter function

tests/filter.test.js

@@ -0,0 +1,68 @@
+import filter from '../src/filter';
+
+describe('every', () => {
+  test('should return an empty object if the object specified isn\'t an object', () => {
+    const filtered = filter('test', () => {});
+
+    expect(typeof filtered).toBe('object');
+  });
+
+  test('should return an empty object if the object specified is empty', () => {
+    const filtered = filter({}, () => {});
+
+    expect(typeof filtered).toBe('object');
+  });
+
+  test('should return an empty object if the iterator isn\'t provided', () => {
+    const filtered = filter({});
+
+    expect(typeof filtered).toBe('object');
+  });
+
+  test('should return an empty object if the iterator isn\'t a function', () => {
+    const filtered = filter({}, 'test');
+
+    expect(typeof filtered).toBe('object');
+  });
+
+  test('should return the filtered values', () => {
+    const obj = {
+      a: 1,
+      b: 2,
+      c: 3,
+    };
+    const filtered = filter(obj, (key, value) => value > 2);
+
+    expect(Object.keys(filtered).length).toBe(1);
+  });
+
+  test('should return the filtered values including deep object values when follow is true', () => {
+    const obj = {
+      a: 1,
+      b: 2,
+      c: 3,
+      d: {
+        e: 4,
+        f: 5,
+      },
+    };
+    const filtered = filter(obj, (key, value) => value > 2, true);
+
+    expect(Object.keys(filtered).length).toBe(2);
+  });
+
+  test('should return the filtered values without filtering deep object values when follow is false', () => {
+    const obj = {
+      a: 1,
+      b: 2,
+      c: 3,
+      d: {
+        e: 4,
+        f: 5,
+      },
+    };
+    const filtered = filter(obj, (key, value) => value > 2, false);
+
+    expect(Object.keys(filtered).length).toBe(1);
+  });
+});