test: TT-332 unit test on the dark mode component

src/app/modules/shared/components/dark-mode/dark-mode.component.spec.ts

@@ -41,6 +41,27 @@ describe('DarkModeComponent', () => {
     expect(component.theme).toBe('light');
   });
 
+  it('should be light theme if only the theme property exists in local storage and not its value', () => {
+    localStorage.setItem('theme', '');
+    component.checkThemeInLocalStorage();
+    expect(component.theme).toBe('light');
+  });
+
+  it('should switch to dark theme if the theme property is light and vice versa', () => {
+    component.theme = component.setTheme();
+    expect(component.theme).toBe('dark');
+    component.theme = component.setTheme();
+    expect(component.theme).toBe('light');
+  });
+
+  it('should add the dark class in the html tag to apply dark mode', () => {
+    component.theme = 'dark';
+    component.addOrRemoveDarkMode();
+    fixture.detectChanges();
+    const htmlContainsDarkClass = document.documentElement.classList.contains('dark');
+    expect(htmlContainsDarkClass).toBe(true);
+  });
+
   it('should be changed to dark mode if the mode toggle is selected', () => {
     component.themeToggle.nativeElement.click();
     fixture.detectChanges();

src/app/modules/shared/components/dark-mode/dark-mode.component.ts

@@ -39,6 +39,10 @@ export class DarkModeComponent implements AfterViewInit {
     return this.theme === 'dark' ? true : false;
   }
 
+  setTheme(): string {
+    return this.isDarkTheme() ? 'light' : 'dark';
+  }
+
   addOrRemoveDarkMode(): void {
     if (this.isDarkTheme()) {
       document.documentElement.classList.add('dark');
@@ -48,11 +52,7 @@ export class DarkModeComponent implements AfterViewInit {
   }
 
   changeToDarkOrLightTheme(): void {
-    if (this.isDarkTheme()) {
-      this.theme = 'light';
-    } else {
-      this.theme = 'dark';
-    }
+    this.theme = this.setTheme();
     this.setLocalStorageTheme(this.theme);
     this.switchThemeToggleStyles(this.theme);
     this.addOrRemoveDarkMode();