added pipe tests

src/app/pipes/ensure-https.pipe.spec.ts

@@ -1,8 +1,32 @@
 import { EnsureHttpsPipe } from './ensure-https.pipe';
 
 describe('EnsureHttpsPipe', () => {
-  it('create an instance', () => {
-    const pipe = new EnsureHttpsPipe();
-    expect(pipe).toBeTruthy();
-  });
+    it('create an instance', () => {
+        const pipe = new EnsureHttpsPipe();
+        expect(pipe).toBeTruthy();
+    });
+
+    it('support null value', () => {
+        const val = null;
+        const pipe = new EnsureHttpsPipe();
+        const result = pipe.transform(val);
+
+        expect(result).toBe(null);
+    });
+
+    it('support not transform https://', () => {
+        const val = 'https://my-link.com';
+        const pipe = new EnsureHttpsPipe();
+        const result = pipe.transform(val);
+
+        expect(result).toBe(val);
+    });
+
+    it('support transform http:// to https://', () => {
+        const val = 'http://my-link.com';
+        const pipe = new EnsureHttpsPipe();
+        const result = pipe.transform(val);
+
+        expect(result).toBe('https://my-link.com');
+    });
 });