🧪 Add tests for subscribe method

src/__tests__/Squawk.subscribe.test.ts

@@ -0,0 +1,62 @@
+import createStore from "../Squawk";
+
+describe("Squawk subscribe", () => {
+  it("should notify subscriber when the subscribed context is updated", () => {
+    const store = createStore({
+      testProp: "initial",
+      otherProp: 1
+    });
+
+    const callback = jest.fn();
+    const unsubscribe = store.subscribe("testProp", callback);
+
+    // Update the subscribed property
+    store.update({ testProp: "updated" });
+
+    // The subscriber should be notified with the new value
+    expect(callback).toHaveBeenCalledTimes(1);
+    expect(callback).toHaveBeenCalledWith("updated");
+
+    unsubscribe();
+  });
+
+  it("should not notify subscriber when an unrelated context is updated", () => {
+    const store = createStore({
+      testProp: "initial",
+      otherProp: 1
+    });
+
+    const callback = jest.fn();
+    store.subscribe("testProp", callback);
+
+    // Update an unrelated property
+    store.update({ otherProp: 2 });
+
+    // The subscriber should not be notified
+    expect(callback).not.toHaveBeenCalled();
+  });
+
+  it("should no longer notify subscriber after unsubscribe is called", () => {
+    const store = createStore({
+      testProp: "initial"
+    });
+
+    const callback = jest.fn();
+    const unsubscribe = store.subscribe("testProp", callback);
+
+    // Update the subscribed property
+    store.update({ testProp: "updated" });
+
+    expect(callback).toHaveBeenCalledTimes(1);
+    expect(callback).toHaveBeenCalledWith("updated");
+
+    // Unsubscribe
+    unsubscribe();
+
+    // Update the property again
+    store.update({ testProp: "updated again" });
+
+    // The subscriber should not be notified a second time
+    expect(callback).toHaveBeenCalledTimes(1);
+  });
+});