[IMP] components: add hooks mechanism

part of #194

tests/hooks.test.ts

@@ -0,0 +1,132 @@
+import { makeTestEnv, makeTestFixture, nextTick } from "./helpers";
+import { Component, Env } from "../src/component/component";
+import { useState, onMounted, onWillUnmount } from "../src/hooks";
+import { xml } from "../src/tags";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+// We create before each test:
+// - fixture: a div, appended to the DOM, intended to be the target of dom
+//   manipulations.  Note that it is removed after each test.
+// - env: a WEnv, necessary to create new components
+
+let fixture: HTMLElement;
+let env: Env;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+  env = makeTestEnv();
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+describe("hooks", () => {
+  test("can use a state hook", async () => {
+    class Counter extends Component<any, any> {
+      static template = xml`<div><t t-esc="counter.value"/></div>`;
+      counter = useState({ value: 42 });
+    }
+    const counter = new Counter(env);
+    await counter.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>42</div>");
+    counter.counter.value = 3;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div>3</div>");
+  });
+
+  test("can use onMounted, onWillUnmount", async () => {
+    const steps: string[] = [];
+    function useMyHook() {
+      onMounted(() => {
+        steps.push("mounted");
+      });
+      onWillUnmount(() => {
+        steps.push("willunmount");
+      });
+    }
+    class MyComponent extends Component<any, any> {
+      static template = xml`<div>hey</div>`;
+      constructor(env) {
+        super(env);
+        useMyHook();
+      }
+    }
+    const component = new MyComponent(env);
+    await component.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>hey</div>");
+    expect(steps).toEqual(["mounted"]);
+    component.unmount();
+    expect(fixture.innerHTML).toBe("");
+    expect(steps).toEqual(["mounted", "willunmount"]);
+  });
+
+  test("mounted, willUnmount, onMounted, onWillUnmount order", async () => {
+    const steps: string[] = [];
+    function useMyHook() {
+      onMounted(() => {
+        steps.push("hook:mounted");
+      });
+      onWillUnmount(() => {
+        steps.push("hook:willunmount");
+      });
+    }
+    class MyComponent extends Component<any, any> {
+      static template = xml`<div>hey</div>`;
+      constructor(env) {
+        super(env);
+        useMyHook();
+      }
+      mounted() {
+        steps.push("comp:mounted");
+      }
+      willUnmount() {
+        steps.push("comp:willunmount");
+      }
+    }
+    const component = new MyComponent(env);
+    await component.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>hey</div>");
+    component.unmount();
+    expect(fixture.innerHTML).toBe("");
+    expect(steps).toEqual(["comp:mounted", "hook:mounted", "hook:willunmount", "comp:willunmount"]);
+  });
+
+  test("two different call to mounted/willunmount should work", async () => {
+    const steps: string[] = [];
+    function useMyHook(i) {
+      onMounted(() => {
+        steps.push("hook:mounted" + i);
+      });
+      onWillUnmount(() => {
+        steps.push("hook:willunmount" + i);
+      });
+    }
+    class MyComponent extends Component<any, any> {
+      static template = xml`<div>hey</div>`;
+      constructor(env) {
+        super(env);
+        useMyHook(1);
+        useMyHook(2);
+      }
+    }
+    const component = new MyComponent(env);
+    await component.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div>hey</div>");
+    component.unmount();
+    expect(fixture.innerHTML).toBe("");
+    expect(steps).toEqual([
+      "hook:mounted1",
+      "hook:mounted2",
+      "hook:willunmount2",
+      "hook:willunmount1"
+    ]);
+  });
+});