1 files changed, 158 insertions, 0 deletions
diff --git a/spec/javascripts/lib/utils/ajax_cache_spec.js b/spec/javascripts/lib/utils/ajax_cache_spec.js
new file mode 100644
index 00000000000..e1747a82329
--- /dev/null
+++ b/spec/javascripts/lib/utils/ajax_cache_spec.js
@@ -0,0 +1,158 @@
+import AjaxCache from '~/lib/utils/ajax_cache';
+
+describe('AjaxCache', () => {
+  const dummyEndpoint = '/AjaxCache/dummyEndpoint';
+  const dummyResponse = {
+    important: 'dummy data',
+  };
+
+  beforeEach(() => {
+    AjaxCache.internalStorage = { };
+    AjaxCache.pendingRequests = { };
+  });
+
+  describe('get', () => {
+    it('returns undefined if cache is empty', () => {
+      const data = AjaxCache.get(dummyEndpoint);
+
+      expect(data).toBe(undefined);
+    });
+
+    it('returns undefined if cache contains no matching data', () => {
+      AjaxCache.internalStorage['not matching'] = dummyResponse;
+
+      const data = AjaxCache.get(dummyEndpoint);
+
+      expect(data).toBe(undefined);
+    });
+
+    it('returns matching data', () => {
+      AjaxCache.internalStorage[dummyEndpoint] = dummyResponse;
+
+      const data = AjaxCache.get(dummyEndpoint);
+
+      expect(data).toBe(dummyResponse);
+    });
+  });
+
+  describe('hasData', () => {
+    it('returns false if cache is empty', () => {
+      expect(AjaxCache.hasData(dummyEndpoint)).toBe(false);
+    });
+
+    it('returns false if cache contains no matching data', () => {
+      AjaxCache.internalStorage['not matching'] = dummyResponse;
+
+      expect(AjaxCache.hasData(dummyEndpoint)).toBe(false);
+    });
+
+    it('returns true if data is available', () => {
+      AjaxCache.internalStorage[dummyEndpoint] = dummyResponse;
+
+      expect(AjaxCache.hasData(dummyEndpoint)).toBe(true);
+    });
+  });
+
+  describe('remove', () => {
+    it('does nothing if cache is empty', () => {
+      AjaxCache.remove(dummyEndpoint);
+
+      expect(AjaxCache.internalStorage).toEqual({ });
+    });
+
+    it('does nothing if cache contains no matching data', () => {
+      AjaxCache.internalStorage['not matching'] = dummyResponse;
+
+      AjaxCache.remove(dummyEndpoint);
+
+      expect(AjaxCache.internalStorage['not matching']).toBe(dummyResponse);
+    });
+
+    it('removes matching data', () => {
+      AjaxCache.internalStorage[dummyEndpoint] = dummyResponse;
+
+      AjaxCache.remove(dummyEndpoint);
+
+      expect(AjaxCache.internalStorage).toEqual({ });
+    });
+  });
+
+  describe('retrieve', () => {
+    let ajaxSpy;
+
+    beforeEach(() => {
+      spyOn(jQuery, 'ajax').and.callFake(url => ajaxSpy(url));
+    });
+
+    it('stores and returns data from Ajax call if cache is empty', (done) => {
+      ajaxSpy = (url) => {
+        expect(url).toBe(dummyEndpoint);
+        const deferred = $.Deferred();
+        deferred.resolve(dummyResponse);
+        return deferred.promise();
+      };
+
+      AjaxCache.retrieve(dummyEndpoint)
+      .then((data) => {
+        expect(data).toBe(dummyResponse);
+        expect(AjaxCache.internalStorage[dummyEndpoint]).toBe(dummyResponse);
+      })
+      .then(done)
+      .catch(fail);
+    });
+
+    it('makes no Ajax call if request is pending', () => {
+      const responseDeferred = $.Deferred();
+
+      ajaxSpy = (url) => {
+        expect(url).toBe(dummyEndpoint);
+        // neither reject nor resolve to keep request pending
+        return responseDeferred.promise();
+      };
+
+      const unexpectedResponse = data => fail(`Did not expect response: ${data}`);
+
+      AjaxCache.retrieve(dummyEndpoint)
+      .then(unexpectedResponse)
+      .catch(fail);
+
+      AjaxCache.retrieve(dummyEndpoint)
+      .then(unexpectedResponse)
+      .catch(fail);
+
+      expect($.ajax.calls.count()).toBe(1);
+    });
+
+    it('returns undefined if Ajax call fails and cache is empty', (done) => {
+      const dummyStatusText = 'exploded';
+      const dummyErrorMessage = 'server exploded';
+      ajaxSpy = (url) => {
+        expect(url).toBe(dummyEndpoint);
+        const deferred = $.Deferred();
+        deferred.reject(null, dummyStatusText, dummyErrorMessage);
+        return deferred.promise();
+      };
+
+      AjaxCache.retrieve(dummyEndpoint)
+      .then(data => fail(`Received unexpected data: ${JSON.stringify(data)}`))
+      .catch((error) => {
+        expect(error.message).toBe(`${dummyEndpoint}: ${dummyErrorMessage}`);
+        expect(error.textStatus).toBe(dummyStatusText);
+        done();
+      })
+      .catch(fail);
+    });
+
+    it('makes no Ajax call if matching data exists', (done) => {
+      AjaxCache.internalStorage[dummyEndpoint] = dummyResponse;
+      ajaxSpy = () => fail(new Error('expected no Ajax call!'));
+
+      AjaxCache.retrieve(dummyEndpoint)
+      .then((data) => {
+        expect(data).toBe(dummyResponse);
+      })
+      .then(done)
+      .catch(fail);
+    });
+  });
+});