diff --git a/apps/demo/src/app/app.component.spec.ts b/apps/demo/src/app/app.component.spec.ts
index fb9c302..e57f3c9 100644
--- a/apps/demo/src/app/app.component.spec.ts
+++ b/apps/demo/src/app/app.component.spec.ts
@@ -1,27 +1,64 @@
 import { ComponentFixture, TestBed } from '@angular/core/testing';
+import { By } from '@angular/platform-browser';
 import { RouterTestingModule } from '@angular/router/testing';
 
 import { AppComponent } from './app.component';
+import { ColorSchemeSwitchComponent } from './components/color-scheme-switch/color-scheme-switch.component';
 
 describe('AppComponent', () => {
     let fixture: ComponentFixture<AppComponent>;
 
     beforeEach(async () => {
         await TestBed.configureTestingModule({
-            imports: [ AppComponent, RouterTestingModule ]
+            imports: [AppComponent, RouterTestingModule]
         }).compileComponents();
 
         fixture = TestBed.createComponent(AppComponent);
         fixture.detectChanges();
     });
 
-    it('should render title', () => {
-        const compiled = fixture.nativeElement as HTMLElement;
+    describe('counter', () => {
+        it('should initially be 0', () => {
+            expect(fixture.componentInstance.counter()).toBe(0);
+        });
 
-        expect(compiled.querySelector('h1')?.textContent).toContain('@bynary/composables');
+        it('should be incremented by 1 after calling incrementCounter', () => {
+            fixture.componentInstance.incrementCounter();
+
+            expect(fixture.componentInstance.counter()).toBe(1);
+
+            fixture.componentInstance.incrementCounter();
+
+            expect(fixture.componentInstance.counter()).toBe(2);
+        });
     });
 
-    it(`should have as title 'demo'`, () => {
-        expect(fixture.componentInstance.title()).toEqual('@bynary/composables');
+    describe('title', () => {
+        it(`should have the correct title`, () => {
+            expect(fixture.componentInstance.title()).toEqual('@bynary/composables');
+        });
+
+        it('should render the title inside a h1', () => {
+            const h1 = fixture.debugElement.query(By.css('h1'));
+
+            expect(h1.nativeElement.textContent).toContain('@bynary/composables');
+        });
+
+        it('should bind the title to the document', () => {
+            expect(document.title).toContain('@bynary/composables');
+        });
+
+        it('should include the click counter after the first click', () => {
+            fixture.componentInstance.incrementCounter();
+
+            expect(fixture.componentInstance.title()).toEqual('@bynary/composables - Clicks: 1');
+        });
+    });
+
+    it('should render the color-scheme-switch component', () => {
+        const predicate = By.directive(ColorSchemeSwitchComponent);
+        const colorSwitch = fixture.debugElement.query(predicate);
+
+        expect(colorSwitch).toBeTruthy();
     });
 });
diff --git a/apps/demo/src/app/components/button/button.component.spec.ts b/apps/demo/src/app/components/button/button.component.spec.ts
index 7c4b523..0b63f90 100644
--- a/apps/demo/src/app/components/button/button.component.spec.ts
+++ b/apps/demo/src/app/components/button/button.component.spec.ts
@@ -8,7 +8,7 @@ describe('ButtonComponent', () => {
 
     beforeEach(async () => {
         await TestBed.configureTestingModule({
-            imports: [ ButtonComponent ]
+            imports: [ButtonComponent]
         }).compileComponents();
 
         fixture = TestBed.createComponent(ButtonComponent);
@@ -19,4 +19,120 @@ describe('ButtonComponent', () => {
     it('should create', () => {
         expect(component).toBeTruthy();
     });
+
+    it('should have the correct base class', () => {
+        expect(fixture.debugElement.classes).toHaveProperty('c-button', true);
+    });
+
+    describe('the `type` property', () => {
+        it('should have the correct default value', () => {
+            expect(component.type()).toEqual('button');
+        });
+
+        it('should be changeable', () => {
+            component.type.set('submit');
+
+            expect(component.type()).toEqual('submit');
+        });
+
+        it('should be bound to the `type` attribute on the component', () => {
+            expect(fixture.debugElement.attributes['type']).toEqual('button');
+        });
+    });
+
+    describe('the `isDisabled` property', () => {
+        it('should have the correct initial value', () => {
+            expect(component.isDisabled()).toBe(false);
+        });
+
+        it('should be changeable', () => {
+            component.isDisabled.set(true);
+
+            expect(component.isDisabled()).toBe(true);
+        });
+
+        it('should be bound to the `disabled` attribute on the component', () => {
+            expect(fixture.debugElement.attributes['disabled']).toBeFalsy();
+
+            component.isDisabled.set(true);
+
+            fixture.detectChanges();
+
+            expect(fixture.debugElement.attributes['disabled']).toEqual('');
+        });
+
+        it('should be affect the `tabindex` attribute on the component', () => {
+            expect(fixture.debugElement.attributes['tabindex']).toEqual('0');
+
+            component.isDisabled.set(true);
+
+            fixture.detectChanges();
+
+            expect(fixture.debugElement.attributes['tabindex']).toEqual('-1');
+        });
+    });
+
+    describe('the `isLoading` property', () => {
+        it('should have the correct initial value', () => {
+            expect(component.isLoading()).toBe(false);
+        });
+
+        it('should be changeable', () => {
+            component.isLoading.set(true);
+
+            expect(component.isLoading()).toBe(true);
+        });
+
+        it('should be bound to the `c-button--is-loading` class on the component', () => {
+            expect(fixture.debugElement.classes).not.toHaveProperty('c-button--is-loading');
+
+            component.isLoading.set(true);
+
+            fixture.detectChanges();
+
+            expect(fixture.debugElement.classes).toHaveProperty('c-button--is-loading', true);
+        });
+    });
+
+    describe('the `appearance` property', () => {
+        it('should have the correct initial value', () => {
+            expect(component.appearance()).toBe('solid');
+        });
+
+        it('should be changeable', () => {
+            component.appearance.set('outline');
+
+            expect(component.appearance()).toBe('outline');
+        });
+
+        it('should be bound as a modifier class on the component', () => {
+            expect(fixture.debugElement.classes).toHaveProperty('c-button--solid', true);
+
+            component.appearance.set('outline');
+
+            fixture.detectChanges();
+
+            expect(fixture.debugElement.classes).toHaveProperty('c-button--outline', true);
+        });
+    });
+
+    describe('the `color` property', () => {
+        it('should have the correct initial value', () => {
+            expect(component.color()).toBeUndefined();
+        });
+
+        it('should be changeable', () => {
+            component.color.set('red');
+
+            expect(component.color()).toBe('red');
+        });
+
+        it('should be bound as a modifier class on the component', () => {
+            component.color.set('red');
+
+            fixture.detectChanges();
+
+            expect(fixture.debugElement.classes).toHaveProperty('c-button--color-red', true);
+        });
+    });
 });
diff --git a/apps/demo/src/app/components/color-scheme-switch/color-scheme-switch.component.spec.ts b/apps/demo/src/app/components/color-scheme-switch/color-scheme-switch.component.spec.ts
index 71f5206..c013fbd 100644
--- a/apps/demo/src/app/components/color-scheme-switch/color-scheme-switch.component.spec.ts
+++ b/apps/demo/src/app/components/color-scheme-switch/color-scheme-switch.component.spec.ts
@@ -1,14 +1,14 @@
 import { ComponentFixture, TestBed } from '@angular/core/testing';
+
 import { ColorSchemeSwitchComponent } from './color-scheme-switch.component';
 
 describe('ColorSchemeSwitchComponent', () => {
     let component: ColorSchemeSwitchComponent;
     let fixture: ComponentFixture<ColorSchemeSwitchComponent>;
 
-
     beforeEach(async () => {
         await TestBed.configureTestingModule({
-            imports: [ ColorSchemeSwitchComponent ]
+            imports: [ColorSchemeSwitchComponent]
         }).compileComponents();
 
         fixture = TestBed.createComponent(ColorSchemeSwitchComponent);
@@ -16,8 +16,69 @@ describe('ColorSchemeSwitchComponent', () => {
         fixture.detectChanges();
     });
 
+    afterEach(() => {
+        localStorage.clear();
+    });
 
     it('should create', () => {
         expect(component).toBeTruthy();
     });
+
+    describe('colorScheme', () => {
+        it('should have the correct default value', () => {
+            expect(component.colorScheme.preferred()).toBeNull();
+            expect(component.colorScheme.store()).toBeUndefined();
+            expect(component.colorScheme.resolved()).toEqual('light');
+        });
+
+        it('should be changeable', () => {
+            component.colorScheme.store.set('dark');
+
+            expect(component.colorScheme.resolved()).toEqual('dark');
+        });
+
+        it('should be bound to the `color-scheme` attribute on the component', () => {
+            expect((document.firstElementChild as HTMLElement).getAttribute('color-scheme')).toEqual('light');
+
+            component.colorScheme.store.set('dark');
+
+            fixture.detectChanges();
+
+            expect((document.firstElementChild as HTMLElement).getAttribute('color-scheme')).toEqual('dark');
+        });
+
+        it('should store the value in localStorage', () => {
+            expect(localStorage.getItem('color-scheme')).toEqual(null);
+
+            component.colorScheme.store.set('dark');
+            fixture.detectChanges();
+
+            expect(localStorage.getItem('color-scheme')).toEqual('dark');
+        });
+    });
+
+    describe('onClick', () => {
+        it('should toggle the color scheme', () => {
+            expect(component.colorScheme.resolved()).toEqual('light');
+
+            fixture.debugElement.triggerEventHandler('click');
+            fixture.detectChanges();
+
+            expect(component.colorScheme.resolved()).toEqual('dark');
+
+            fixture.debugElement.triggerEventHandler('click');
+            fixture.detectChanges();
+
+            expect(component.colorScheme.resolved()).toEqual('light');
+        });
+    });
+
+    it('should display a matching emoji for the current color scheme', () => {
+        expect(fixture.debugElement.nativeElement.textContent).toEqual('🌝');
+
+        component.colorScheme.store.set('dark');
+        fixture.detectChanges();
+
+        expect(fixture.debugElement.nativeElement.textContent).toEqual('🌚');
+    });
 });