Add type definition for test helper import (#481)

* Add type definition for test helper import

* types: add support for `hbs(template, options)` invocation

* types: improve hbs usage examples in docstring

* Drop weirdly-added tests file

* types: explicitly set location in package.json

index.d.ts

@@ -0,0 +1,65 @@
+// Using the same "brand" as the types for `htmlbars-inline-precompile` for
+// backwards compatibility. The actual value of the brand doesn't matter; it is
+// only important that it (a) is distinct and (b) interoperates with existing
+// uses of the `hbs` export from `htmlbars-inline-precompile` [1].
+//
+// [1]: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/24a21e0b8ec7eccdec781d7513bfa5947f1c6e20/types/ember/index.d.ts#L540:L542
+//
+// Note that we *intentionally* do not export this; the details are irrelevant
+// to consumers. The point is simply to have a *distinct* type that is therefore
+// not substitutable for just any other type.
+interface TemplateFactory {
+  __htmlbars_inline_precompile_template_factory: any;
+}
+
+export interface PrecompileOptions {
+  moduleName?: string;
+  parseOptions?: {
+    srcName?: string;
+  };
+}
+
+/**
+ * A helper for rendering components.
+ *
+ * @param tagged The template to render.
+ *
+ * ## Usage
+ *
+ * ### With tagged template
+ *
+ * ```ts
+ * import { module, test } from 'qunit';
+ * import { setupRenderingTest } from 'ember-qunit';
+ * import { render } from '@ember/test-helpers';
+ * import { hbs } from 'ember-cli-htmlbars';
+ *
+ * module('demonstrate hbs usage', function(hooks) {
+ *   setupRenderingTest(hooks);
+ *
+ *   test('you can render things', function(assert) {
+ *     await render(hbs`<TestingComponents @isCool={{true}} />`);
+ *     assert.ok(true);
+ *   });
+ * });
+ * ```
+ *
+ * ## With string and options
+ *
+ * ```ts
+ * import Component from '@glimmer/component';
+ * import { setComponentTemplate } from '@ember/component';
+ * import { hbs } from 'ember-cli-htmlbars';
+ *
+ * class Hello extends Component {
+ *   greeting = 'hello world';
+ * }
+ *
+ * setComponentTemplate(
+ *   hbs('<p>{{this.greeting}}</p>', { moduleName: 'hello.hbs' }),
+ *   MyComponent
+ * );
+ * ```
+ */
+export function hbs(template: string, options?: PrecompileOptions): TemplateFactory;
+export function hbs(tagged: TemplateStringsArray): TemplateFactory;

package.json

@@ -20,6 +20,7 @@
     "lib/"
   ],
   "main": "lib/index.js",
+  "types": "index.d.ts",
   "scripts": {
     "build": "ember build",
     "lint:hbs": "ember-template-lint .",