[tests][perf] added perf() tests -> 100% coverage

bridge/e2e/perf/perf.e2e.js

@@ -0,0 +1,34 @@
+describe('perf()', () => {
+  describe('setPerformanceCollectionEnabled()', () => {
+    it('true', async () => {
+      await firebase.perf().setPerformanceCollectionEnabled(true);
+    });
+
+    it('false', async () => {
+      await firebase.perf().setPerformanceCollectionEnabled(false);
+    });
+
+    xit('errors if not boolean', async () => {
+      // TODO add validations to lib
+      await firebase.perf().setPerformanceCollectionEnabled();
+    });
+  });
+
+  describe('newTrace()', () => {
+    it('returns an instance of Trace', async () => {
+      const trace = firebase.perf().newTrace('foo');
+      trace.constructor.name.should.be.equal('Trace');
+    });
+
+    xit('errors if identifier not a string', async () => {
+      // TODO add validations to lib
+      try {
+        firebase.perf().newTrace([1, 2, 3, 4]);
+      } catch (e) {
+        return undefined;
+      }
+
+      throw new Error('Trace did not error on invalid identifier');
+    });
+  });
+});

bridge/e2e/perf/trace.e2e.js

@@ -0,0 +1,28 @@
+describe('perf()', () => {
+  describe('Trace', () => {
+    it('start() & stop()', async () => {
+      const trace = firebase.perf().newTrace('bar');
+      await trace.start();
+      await trace.stop();
+    });
+
+    describe('incrementCounter()', () => {
+      it('accepts a string event', async () => {
+        const trace = firebase.perf().newTrace('bar');
+        await trace.start();
+        await trace.incrementCounter('fooby');
+        await trace.incrementCounter('fooby');
+        await trace.incrementCounter('fooby');
+        await trace.incrementCounter('fooby');
+        await trace.stop();
+      });
+
+      xit('errors if event is not a string', async () => {
+        const trace = firebase.perf().newTrace('bar');
+        await trace.start();
+        await trace.incrementCounter([1, 2, 3, 4]);
+        await trace.stop();
+      });
+    });
+  });
+});