Get helpers tests to 90% code coverage

Author: haejinjo

src/backend/__tests__/helpers.test.ts

@@ -13,46 +13,48 @@ import { throttle, getHooksNames } from '../helpers';
 // Newer Enzyme versions require an adapter to a particular version of React
 configure({ adapter: new Adapter() });
 
+// Replace any setTimeout functions with jest timer
+jest.useFakeTimers();
+
 describe('AST Unit Tests', () => {
 
   describe('throttle', () => {
     let mockFunc;
-    let throttleOutput;
+    let throttledMockFunc;
 
     beforeEach(() => {
-      // Replace any setTimeout functions with jest timer
-      jest.useFakeTimers();
       mockFunc = jest.fn();
-      throttleOutput = throttle(mockFunc, 1000);
+      throttledMockFunc = throttle(mockFunc, 1000);
     });
 
     it('Should return a function', () => {
-      expect(typeof throttleOutput).toBe('function');
+      expect(typeof throttledMockFunc).toBe('function');
+    });
+
+    it('throttles subsequent fire attempts into one shot after cooldown', () => {
+      throttledMockFunc();
+      expect(mockFunc).toHaveBeenCalledTimes(1);
+      jest.advanceTimersByTime(20);
+      throttledMockFunc();
+      jest.advanceTimersByTime(20);
+      throttledMockFunc();
+      jest.advanceTimersByTime(20);
+      throttledMockFunc();
+      expect(mockFunc).toHaveBeenCalledTimes(1);
+
+      jest.advanceTimersByTime(941);
+
+      expect(mockFunc).toHaveBeenCalledTimes(2);
     });
 
     it('Should only invoke function', () => {
-      /*
-        How Throttle Works
-        1. INIT isOnCooldown and isCallQueued to false
-
-        2. first time you call throttledFunc:
-            1. invoke input function
-            2. isOnCooldown set to true, isCallQueued set to false
-            3. Invoke `runAfterTimeout` after X milliseconds (using setTimeout)
-              - invoke input function
-              - isOnCooldown set to false
-        3. next time you call
-          TO BE CONTINUED...
-      */
-
-      // Expect the mock function we pass in to only be called at most every X milliseconds
+      // Because we haven't invoked returned function from throttle
+      // mock func should not have been called yet
       expect(mockFunc).not.toHaveBeenCalled();
 
-      // Invoke returned timer function from throttle
-      throttleOutput();
-      // At this point, setTimeout has been invoked
-      expect(setTimeout).toHaveBeenCalledTimes(1);
-      expect(setTimeout).toHaveBeenLastCalledWith(expect.any(Function), 1000);
+      throttledMockFunc();
+
+      expect(mockFunc).toHaveBeenCalledTimes(1);
     });
   });
 
@@ -73,17 +75,22 @@ describe('AST Unit Tests', () => {
       expect(getHooksNames(elementType)).toEqual(['testCount', 'setTestCount']);
     });
 
-    it.skip('Should output the right number of properties when taking in multiple function definitions', () => {
-      const useState = 'const singleUseStateTest = () => { const [testCount, setTestCount] = useState(0); const [age, setAge] = useState(20); return ( <div> <p> You clicked this {testCount} times </p> <button onClick={() => setTestCount(testCount + 1)}>+1</button> <button onClick={() => setTestCount(testCount - 1)}>-1</button> <p> You are {age} years old! </p> <button onClick={() => setAge(age + 1)}>Get Older</button> <hr /> </div>)';
-
-      const expectedObject = {
-        _useState: 'testCount',
-        _useState2: 'setTestCount',
-        _useState3: 'age',
-        _useState4: 'setAge',
-      };
-      expect(getHooksNames(useState)).toEqual(expectedObject);
-      expect(Object.keys(getHooksNames(useState))).toHaveLength(4);
+    it('Should output the right number of properties when taking in multiple function definitions', () => {
+      const elementType = `function SingleUseFakeComponent() { 
+                            const [testCount, setTestCount] = useState(0);
+                            const [biscuitCount, setBiscuitCount] = useState(0);
+                            const age = 20; 
+                            return (<div> <p> You clicked this {testCount} times </p>
+                                    <button onClick={() => setTestCount(testCount + 1)}>+1</button>
+                                    <button onClick={() => setTestCount(testCount - 1)}>-1</button> <p>
+                                    You are {age} years old! </p>
+                                    <button onClick={age => age + 1}>Get Older</button>
+                                    <hr /> 
+                                    </div>);
+                          }`;
+
+      expect(getHooksNames(elementType)).toEqual(['testCount', 'setTestCount', 'biscuitCount', 'setBiscuitCount']);
+      expect(Object.keys(getHooksNames(elementType))).toHaveLength(4);
     });
 
     it('Should ignore any non-hook definitions', () => {
@@ -103,18 +110,30 @@ describe('AST Unit Tests', () => {
       expect(Object.keys(getHooksNames(elementType))).toHaveLength(expectedNumHookVariables);
     });
 
-    it.skip('Should return an empty object if no hooks found', () => {
-      const useState = 'const singleUseStateTest = () => { const age = 20; return ( <div> <p> You are {age} years old! </p> <button onClick={age => age + 1}>Get Older</button> <hr /> </div>)';
+    it('Should return an empty object if no hooks found', () => {
+      const elementType = `function SingleUseFakeComponent() { 
+                            const age = 20; 
+                            return (<div> <p> You clicked this {testCount} times </p>
+                                    <button onClick={() => setTestCount(testCount + 1)}>+1</button>
+                                    <button onClick={() => setTestCount(testCount - 1)}>-1</button> <p>
+                                    You are {age} years old! </p>
+                                    <button onClick={age => age + 1}>Get Older</button>
+                                    <hr /> 
+                                    </div>);
+                          }`;
 
-      expect(getHooksNames(useState)).toBe({});
+      expect(getHooksNames(elementType)).toEqual([]);
     });
 
-    it.skip('Should throw an error if input is invalid javascript', () => {
+    it('Should throw an error if input returns invalid JSX', () => {
       const useState = `const singleUseStateTest = () => { 
                         age: 20; 
-                        return ( <div> <p> You are {age} years old! </p> <button onClick={age + 1}>Get Older</button></div>) }`;
+                        return (<p> You are {age} years old! </p> 
+                                  <button onClick={age + 1}>Get Older</button>
+                                 </div>)
+                        }`;
 
-      expect(getHooksNames(useState)).toThrow();
+      expect(getHooksNames(useState)).toEqual(['unknown']);
     });
   });
 });