fix(cdk/testing): TestElement sendKeys method should not throw if no keys have been specified

Previously, calling `sendKeys` without any keys resulted in an error
being thrown. This is because the first element of the passed arguments
to `sendKeys` has been considered always truthy. This assumption is
wrong since arbitrary amount of arguments can be passed due to the
spread parameter.

Also, calling `sendKeys` without any keys should not result in the
element being focused. Pressing no keys/entering no text, does require
the element to be focused.

Author: devversion

src/cdk/testing/protractor/protractor-element.ts

@@ -100,7 +100,7 @@ export class ProtractorElement implements TestElement {
     const first = modifiersAndKeys[0];
     let modifiers: ModifierKeys;
     let rest: (string | TestKey)[];
-    if (typeof first !== 'string' && typeof first !== 'number') {
+    if (first !== undefined && typeof first !== 'string' && typeof first !== 'number') {
       modifiers = first;
       rest = modifiersAndKeys.slice(1);
     } else {
@@ -113,6 +113,12 @@ export class ProtractorElement implements TestElement {
         .reduce((arr, k) => arr.concat(k), [])
         .map(k => Key.chord(...modifierKeys, k));
 
+    // Do nothing if no keys have been specified. Calling this function with no keys should
+    // not result in a focus event being dispatched.
+    if (keys.length === 0) {
+      return;
+    }
+
     return this.element.sendKeys(...keys);
   }
 

src/cdk/testing/testbed/fake-events/type-in-element.ts

@@ -20,7 +20,7 @@ export function isTextInput(element: Element): element is HTMLInputElement | HTM
 }
 
 /**
- * Focuses an input, sets its value and dispatches
+ * If keys have been specified, focuses an input, sets its value and dispatches
  * the `input` event, simulating the user typing.
  * @param element Element onto which to set the value.
  * @param keys The keys to send to the element.
@@ -30,7 +30,7 @@ export function typeInElement(
     element: HTMLElement, ...keys: (string | {keyCode?: number, key?: string})[]): void;
 
 /**
- * Focuses an input, sets its value and dispatches
+ * If keys have been specified, focuses an input, sets its value and dispatches
  * the `input` event, simulating the user typing.
  * @param element Element onto which to set the value.
  * @param modifiers Modifier keys that are held while typing.
@@ -40,11 +40,12 @@ export function typeInElement(
 export function typeInElement(element: HTMLElement, modifiers: ModifierKeys,
                               ...keys: (string | {keyCode?: number, key?: string})[]): void;
 
-export function typeInElement(element: HTMLElement, ...modifiersAndKeys: any) {
+export function typeInElement(element: HTMLElement, ...modifiersAndKeys: any[]) {
   const first = modifiersAndKeys[0];
   let modifiers: ModifierKeys;
   let rest: (string | {keyCode?: number, key?: string})[];
-  if (typeof first !== 'string' && first.keyCode === undefined && first.key === undefined) {
+  if (first !== undefined && typeof first !== 'string' && first.keyCode === undefined &&
+      first.key === undefined) {
     modifiers = first;
     rest = modifiersAndKeys.slice(1);
   } else {
@@ -56,6 +57,12 @@ export function typeInElement(element: HTMLElement, ...modifiersAndKeys: any) {
           k.split('').map(c => ({keyCode: c.toUpperCase().charCodeAt(0), key: c})) : [k])
       .reduce((arr, k) => arr.concat(k), []);
 
+  // Do nothing if no keys have been specified. Calling this function with no keys should
+  // not result in a focus event being dispatched.
+  if (keys.length === 0) {
+    return;
+  }
+
   triggerFocus(element);
   for (const key of keys) {
     dispatchKeyboardEvent(element, 'keydown', key.keyCode, key.key, element, modifiers);

src/cdk/testing/tests/protractor.e2e.spec.ts

@@ -197,6 +197,17 @@ describe('ProtractorHarnessEnvironment', () => {
       expect(await input.getProperty('value')).toBe('');
     });
 
+    it('sendKeys method should not focus element if no keys have been specified', async () => {
+      const input = await harness.input();
+      expect(await input.isFocused()).toBe(false);
+      await input.sendKeys();
+      expect(await input.isFocused()).toBe(false);
+      await input.sendKeys('');
+      expect(await input.isFocused()).toBe(false);
+      await input.sendKeys('', '');
+      expect(await input.isFocused()).toBe(false);
+    });
+
     it('should be able to click', async () => {
       const counter = await harness.counter();
       expect(await counter.text()).toBe('0');

src/cdk/testing/tests/testbed.spec.ts

@@ -294,6 +294,17 @@ describe('TestbedHarnessEnvironment', () => {
       expect(await input.getProperty('value')).toBe('');
     });
 
+    it('sendKeys method should not focus element if no keys have been specified', async () => {
+      const input = await harness.input();
+      expect(await input.isFocused()).toBe(false);
+      await input.sendKeys();
+      expect(await input.isFocused()).toBe(false);
+      await input.sendKeys('');
+      expect(await input.isFocused()).toBe(false);
+      await input.sendKeys('', '');
+      expect(await input.isFocused()).toBe(false);
+    });
+
     it('should be able to click', async () => {
       const counter = await harness.counter();
       expect(await counter.text()).toBe('0');