test: add test to useParagonTheme hook and paragon utils

src/react/hooks/paragon/useParagonTheme.test.js

@@ -0,0 +1,38 @@
+import { act, renderHook } from '@testing-library/react-hooks';
+import useParagonTheme from './useParagonTheme';
+
+describe('useParagonTheme', () => {
+  it('should return an array with and object that indicates the theme status, and a function', () => {
+    const config = {
+      PARAGON_THEME_URLS: {
+        core: {
+          urls: {
+            default: 'https://cdn.jsdelivr.net/npm/@edx/paragon@$paragonVersion/dist/core.min.css',
+          },
+        },
+        defaults: {
+          light: 'light',
+          dark: 'dark',
+        },
+        variants: {
+          light: {
+            urls: {
+              default: 'https://cdn.jsdelivr.net/npm/@edx/paragon@$paragonVersion/dist/light.min.css',
+            },
+          },
+          dark: {
+            urls: {
+              default: 'https://cdn.jsdelivr.net/npm/@edx/paragon@$paragonVersion/dist/dark.min.css',
+            },
+          },
+        },
+      },
+    };
+
+    const { result } = renderHook(() => useParagonTheme(config));
+    const createdLinksTag = document.head.querySelectorAll('link');
+    act(() => { createdLinksTag.forEach((link) => link.onload()); });
+
+    expect(result.current).toEqual([{ isThemeLoaded: true, themeVariant: 'light' }, expect.any(Function)]);
+  });
+});

src/react/hooks/paragon/utils.test.js

@@ -0,0 +1,95 @@
+import { removeExistingLinks, getDefaultThemeVariant, handleVersionSubstitution } from './utils';
+
+Object.defineProperty(window, 'matchMedia', {
+  writable: true,
+  value: jest.fn().mockImplementation(query => ({
+    matches: true,
+    media: query,
+  })),
+});
+
+const mockGetItem = jest.fn();
+Object.defineProperty(window, 'localStorage', {
+  value: {
+    getItem: mockGetItem,
+  },
+});
+
+describe('removeExistingLinks', () => {
+  afterEach(() => {
+    document.head.innerHTML = '';
+    jest.clearAllMocks();
+  });
+
+  it('should remove all the links in the DOM', () => {
+    document.head.innerHTML = `
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@edx/paragon@$21.0.0/dist/core.min.css">
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@edx/brand@$2.0.0Version/dist/core.min.css">
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@edx/paragon@$21.0.0/dist/light.min.css">
+    `;
+
+    removeExistingLinks(document.querySelectorAll('link'));
+    expect(document.querySelectorAll('link').length).toBe(0);
+  });
+});
+
+describe('getDefaultThemeVariant', () => {
+  it('should return the theme variant according with system preference', () => {
+    const variant = getDefaultThemeVariant({
+      themeVariantDefaults: {
+        light: 'light',
+        dark: 'dark',
+      },
+      themeVariants: {
+        light: {
+          fileName: 'light.min.css',
+        },
+        dark: {
+          fileName: 'dark.min.css',
+        },
+      },
+    });
+    expect(variant).toEqual({ metadata: { fileName: 'dark.min.css' }, name: 'dark' });
+  });
+
+  it('should return the theme variant according with local storage preference', () => {
+    mockGetItem.mockImplementation(() => 'light');
+    const variant = getDefaultThemeVariant({
+      themeVariantDefaults: {
+        light: 'light',
+        dark: 'dark',
+      },
+      themeVariants: {
+        light: {
+          fileName: 'light.min.css',
+        },
+        dark: {
+          fileName: 'dark.min.css',
+        },
+      },
+    });
+    expect(variant).toEqual({ metadata: { fileName: 'light.min.css' }, name: 'light' });
+  });
+
+  it('should return the theme variant configuration as default', () => {
+    const variant = getDefaultThemeVariant({
+      themeVariantDefaults: {
+        light: 'light',
+      },
+      themeVariants: {
+        light: {
+          fileName: 'light.min.css',
+        },
+      },
+    });
+    expect(variant).toEqual({ metadata: { fileName: 'light.min.css' }, name: 'light' });
+  });
+});
+
+describe('handleVersionSubstitution', () => {
+  it('should substitude the paragon version to use', () => {
+    const config = { localVersion: '21.1.1', wildcardKeyword: 'alpha', url: 'https://cdn.jsdelivr.net/npm/@edx/paragon@alpha/dist/core.min.css' };
+    const newLink = handleVersionSubstitution(config);
+    expect(newLink).toBe('https://cdn.jsdelivr.net/npm/@edx/paragon@21.1.1/dist/core.min.css');
+  });
+});