creation of tests for the errorPanel LWC (trailheadapps#207)

force-app/main/default/lwc/errorPanel/__tests__/errorPanel.tests.js

@@ -0,0 +1,78 @@
+import { createElement } from 'lwc';
+import ErrorPanel from 'c/errorPanel';
+
+describe('c-error-panel', () => {
+    afterEach(() => {
+        // The jsdom instance is shared across test cases in a single file so reset the DOM
+        while (document.body.firstChild) {
+            document.body.removeChild(document.body.firstChild);
+        }
+    });
+
+    it('displays a default friendly message', () => {
+        const MESSAGE = 'Error retrieving data';
+
+        // Create initial element
+        const element = createElement('c-error-panel', {
+            is: ErrorPanel
+        });
+        document.body.appendChild(element);
+
+        const messageEl = element.shadowRoot.querySelector('h3');
+        expect(messageEl.textContent).toBe(MESSAGE);
+    });
+
+    it('displays a custom friendly message', () => {
+        const MESSAGE = 'Errors are bad';
+
+        // Create initial element
+        const element = createElement('c-error-panel', {
+            is: ErrorPanel
+        });
+        element.friendlyMessage = MESSAGE;
+        document.body.appendChild(element);
+
+        const messageEl = element.shadowRoot.querySelector('h3');
+        expect(messageEl.textContent).toBe(MESSAGE);
+    });
+
+    it('displays no error details when no errors are passed as parameters', () => {
+        // Create initial element
+        const element = createElement('c-error-panel', {
+            is: ErrorPanel
+        });
+        document.body.appendChild(element);
+
+        const inputEl = element.shadowRoot.querySelector('lightning-input');
+        expect(inputEl).toBeNull();
+    });
+
+    it('displays error details when errors are passed as parameters', () => {
+        const ERROR_MESSAGES_INPUT = [
+            { statusText: 'First bad error' },
+            { statusText: 'Second bad error' }
+        ];
+        const ERROR_MESSAGES_OUTPUT = ['First bad error', 'Second bad error'];
+
+        // Create initial element
+        const element = createElement('c-error-panel', {
+            is: ErrorPanel
+        });
+        element.errors = ERROR_MESSAGES_INPUT;
+        document.body.appendChild(element);
+
+        const inputEl = element.shadowRoot.querySelector('a');
+        inputEl.checked = true;
+        inputEl.dispatchEvent(new CustomEvent('click'));
+
+        // Return a promise to wait for any asynchronous DOM updates. Jest
+        // will automatically wait for the Promise chain to complete before
+        // ending the test and fail the test if the promise rejects.
+        return Promise.resolve().then(() => {
+            const messageTexts = Array.from(
+                element.shadowRoot.querySelectorAll('p')
+            ).map((errorMessage) => (errorMessage = errorMessage.textContent));
+            expect(messageTexts).toEqual(ERROR_MESSAGES_OUTPUT);
+        });
+    });
+});