Initial Commit

test/observables/ReadOnlySubject.test.ts

@@ -0,0 +1,60 @@
+import {jest, describe, it, expect} from 'bun:test';
+import {Subject, ReadOnlySubject} from '../../src/observables';
+
+describe(`A ReadOnlySubject`, () => {
+  it(`exposes the Subject value`, () => {
+    const subject = new Subject<string>(`init-value`);
+    const readOnlySubject = new ReadOnlySubject(subject);
+
+    expect(readOnlySubject.value).toBe(`init-value`);
+  });
+
+  it(`updates the ReadOnlySubject value when set`, () => {
+    const subject = new Subject<string>('init-value');
+    const readOnlySubject = new ReadOnlySubject(subject);
+
+    subject.value = 'some thing';
+
+    expect(readOnlySubject.value).toBe('some thing');
+  });
+
+  it(`notifies subcribers when subscribing`, () => {
+    const subject = new Subject<string>('init-value');
+    const readOnlySubject = new ReadOnlySubject(subject);
+    const listener = jest.fn() as (value: string) => void;
+
+    readOnlySubject.subscribe(listener);
+
+    expect(listener).toHaveBeenCalledWith('init-value');
+  });
+
+  it(`notifies subcribers when value changes`, () => {
+    const subject = new Subject<string>('init-value');
+    const readOnlySubject = new ReadOnlySubject(subject);
+    const listener = jest.fn() as (value: string) => void;
+
+    readOnlySubject.subscribe(listener);
+
+    subject.value = 'some thing';
+
+    expect(listener).toHaveBeenCalledWith('some thing');
+  });
+
+  it(`notifies all subcribers when value changes`, () => {
+    const subject = new Subject<string>('init-value');
+    const readOnlySubject = new ReadOnlySubject(subject);
+    const listener1 = jest.fn() as (value: string) => void;
+    const listener2 = jest.fn() as (value: string) => void;
+    const listener3 = jest.fn() as (value: string) => void;
+
+    readOnlySubject.subscribe(listener1);
+    readOnlySubject.subscribe(listener2);
+    readOnlySubject.subscribe(listener3);
+
+    subject.value = 'some thing';
+
+    expect(listener1).toHaveBeenCalledWith('some thing');
+    expect(listener2).toHaveBeenCalledWith('some thing');
+    expect(listener3).toHaveBeenCalledWith('some thing');
+  });
+});