feat: add Lit renderer directive for select (#3775)

packages/select/lit.d.ts

@@ -0,0 +1 @@
+export * from './src/lit/renderer-directives.js';

packages/select/lit.js

@@ -0,0 +1 @@
+export * from './src/lit/renderer-directives.js';

packages/select/package.json

@@ -22,6 +22,8 @@
   "files": [
     "src",
     "theme",
+    "lit.js",
+    "lit.d.ts",
     "vaadin-*.d.ts",
     "vaadin-*.js"
   ],
@@ -40,6 +42,7 @@
     "@vaadin/input-container": "23.1.0-beta1",
     "@vaadin/item": "23.1.0-beta1",
     "@vaadin/list-box": "23.1.0-beta1",
+    "@vaadin/lit-renderer": "23.1.0-beta1",
     "@vaadin/vaadin-list-mixin": "23.1.0-beta1",
     "@vaadin/vaadin-lumo-styles": "23.1.0-beta1",
     "@vaadin/vaadin-material-styles": "23.1.0-beta1",

packages/select/src/lit/renderer-directives.d.ts

@@ -0,0 +1,59 @@
+/**
+ * @license
+ * Copyright (c) 2017 - 2022 Vaadin Ltd.
+ * This program is available under Apache License Version 2.0, available at https://vaadin.com/license/
+ */
+import { TemplateResult } from 'lit';
+import { DirectiveResult } from 'lit/directive.js';
+import { LitRendererDirective } from '@vaadin/lit-renderer';
+import { Select } from '../vaadin-select.js';
+
+export type SelectLitRenderer = (select: Select) => TemplateResult;
+
+export class SelectRendererDirective extends LitRendererDirective<Select, SelectLitRenderer> {
+  /**
+   * Adds the renderer callback to the select.
+   */
+  addRenderer(): void;
+
+  /**
+   * Runs the renderer callback on the select.
+   */
+  runRenderer(): void;
+
+  /**
+   * Removes the renderer callback from the select.
+   */
+  removeRenderer(): void;
+}
+
+/**
+ * A Lit directive for populating the content of the `<vaadin-select-overlay>` element.
+ *
+ * The directive accepts a renderer callback returning a Lit template and assigns it to the select
+ * via the `renderer` property. The renderer is called once to populate the content when assigned
+ * and whenever a single dependency or an array of dependencies changes.
+ * It is not guaranteed that the renderer will be called immediately (synchronously) in both cases.
+ *
+ * Dependencies can be a single value or an array of values.
+ * Values are checked against previous values with strict equality (`===`),
+ * so the check won't detect nested property changes inside objects or arrays.
+ * When dependencies are provided as an array, each item is checked against the previous value
+ * at the same index with strict equality. Nested arrays are also checked only by strict
+ * equality.
+ *
+ * Example of usage:
+ * ```js
+ * `<vaadin-select
+ *   ${selectRenderer((select) => html`...`)}
+ * ></vaadin-select>`
+ * ```
+ *
+ * @param renderer the renderer callback that returns a Lit template.
+ * @param dependencies a single dependency or an array of dependencies
+ *                     which trigger a re-render when changed.
+ */
+export declare function selectRenderer(
+  renderer: SelectLitRenderer,
+  dependencies?: unknown,
+): DirectiveResult<typeof SelectRendererDirective>;

packages/select/src/lit/renderer-directives.js

@@ -0,0 +1,60 @@
+/**
+ * @license
+ * Copyright (c) 2017 - 2022 Vaadin Ltd.
+ * This program is available under Apache License Version 2.0, available at https://vaadin.com/license/
+ */
+import { directive } from 'lit/directive.js';
+import { LitRendererDirective } from '@vaadin/lit-renderer';
+
+export class SelectRendererDirective extends LitRendererDirective {
+  /**
+   * Adds the renderer callback to the select.
+   */
+  addRenderer() {
+    this.element.renderer = (root, select) => {
+      this.renderRenderer(root, select);
+    };
+  }
+
+  /**
+   * Runs the renderer callback on the select.
+   */
+  runRenderer() {
+    this.element.requestContentUpdate();
+  }
+
+  /**
+   * Removes the renderer callback from the select.
+   */
+  removeRenderer() {
+    this.element.renderer = null;
+  }
+}
+
+/**
+ * A Lit directive for populating the content of the `<vaadin-select-overlay>` element.
+ *
+ * The directive accepts a renderer callback returning a Lit template and assigns it to the select
+ * via the `renderer` property. The renderer is called once to populate the content when assigned
+ * and whenever a single dependency or an array of dependencies changes.
+ * It is not guaranteed that the renderer will be called immediately (synchronously) in both cases.
+ *
+ * Dependencies can be a single value or an array of values.
+ * Values are checked against previous values with strict equality (`===`),
+ * so the check won't detect nested property changes inside objects or arrays.
+ * When dependencies are provided as an array, each item is checked against the previous value
+ * at the same index with strict equality. Nested arrays are also checked only by strict
+ * equality.
+ *
+ * Example of usage:
+ * ```js
+ * `<vaadin-select
+ *   ${selectRenderer((select) => html`...`)}
+ * ></vaadin-select>`
+ * ```
+ *
+ * @param renderer the renderer callback that returns a Lit template.
+ * @param dependencies a single dependency or an array of dependencies
+ *                     which trigger a re-render when changed.
+ */
+export const selectRenderer = directive(SelectRendererDirective);

packages/select/test/lit-renderer-directives.test.js

@@ -0,0 +1,66 @@
+import { expect } from '@esm-bundle/chai';
+import { fixtureSync, nextFrame } from '@vaadin/testing-helpers';
+import sinon from 'sinon';
+import './not-animated-styles.js';
+import '../vaadin-select.js';
+import { html, render } from 'lit';
+import { selectRenderer } from '../lit.js';
+
+async function renderOpenedSelect(container, { content }) {
+  render(
+    html`<vaadin-select opened ${content ? selectRenderer(() => html`${content}`, content) : null}></vaadin-select>`,
+    container,
+  );
+  await nextFrame();
+  return container.querySelector('vaadin-select');
+}
+
+describe('lit renderer directives', () => {
+  let container, select, overlay;
+
+  beforeEach(() => {
+    container = fixtureSync('<div></div>');
+  });
+
+  describe('selectRenderer', () => {
+    describe('basic', () => {
+      beforeEach(async () => {
+        select = await renderOpenedSelect(container, { content: 'Content' });
+        overlay = select.shadowRoot.querySelector('vaadin-select-overlay');
+      });
+
+      it('should set `renderer` property when the directive is attached', () => {
+        expect(select.renderer).to.exist;
+      });
+
+      it('should unset `renderer` property when the directive is detached', async () => {
+        await renderOpenedSelect(container, {});
+        expect(select.renderer).not.to.exist;
+      });
+
+      it('should render the content with the renderer', () => {
+        expect(overlay.textContent).to.equal('Content');
+      });
+
+      it('should re-render the content when a renderer dependency changes', async () => {
+        await renderOpenedSelect(container, { content: 'New Content' });
+        expect(overlay.textContent).to.equal('New Content');
+      });
+    });
+
+    describe('arguments', () => {
+      let rendererSpy;
+
+      beforeEach(async () => {
+        rendererSpy = sinon.spy();
+        render(html`<vaadin-select opened ${selectRenderer(rendererSpy)}></vaadin-select>`, container);
+        await nextFrame();
+        select = container.querySelector('vaadin-select');
+      });
+
+      it('should pass the select instance to the renderer', () => {
+        expect(rendererSpy.firstCall.args[0]).to.equal(select);
+      });
+    });
+  });
+});

packages/select/test/typings/lit.types.ts

@@ -0,0 +1,8 @@
+import { DirectiveResult } from 'lit/directive.js';
+import { SelectLitRenderer, selectRenderer, SelectRendererDirective } from '../../lit.js';
+
+const assertType = <TExpected>(actual: TExpected) => actual;
+
+assertType<(renderer: SelectLitRenderer, dependencies?: unknown) => DirectiveResult<typeof SelectRendererDirective>>(
+  selectRenderer,
+);