From 57591f57547143d73a70e5a52e94267a9ccc200b Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Tue, 16 Nov 2021 18:47:50 +0100
Subject: [PATCH] test-utils: add TestApiProvider

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 packages/test-utils/api-report.md             | 13 +++
 .../src/testUtils/TestApiProvider.tsx         | 94 +++++++++++++++++++
 packages/test-utils/src/testUtils/index.tsx   |  2 +
 3 files changed, 109 insertions(+)
 create mode 100644 packages/test-utils/src/testUtils/TestApiProvider.tsx

diff --git a/packages/test-utils/api-report.md b/packages/test-utils/api-report.md
index 62a8d9f601..38656137a3 100644
--- a/packages/test-utils/api-report.md
+++ b/packages/test-utils/api-report.md
@@ -5,6 +5,7 @@
 ```ts
 import { AnalyticsApi } from '@backstage/core-plugin-api';
 import { AnalyticsEvent } from '@backstage/core-plugin-api';
+import { ApiRef } from '@backstage/core-plugin-api';
 import { ComponentType } from 'react';
 import { ErrorApi } from '@backstage/core-plugin-api';
 import { ErrorApiError } from '@backstage/core-plugin-api';
@@ -175,6 +176,18 @@ export function setupRequestMockHandlers(worker: {
 // @public
 export type SyncLogCollector = () => void;
 
+// @public
+export const TestApiProvider: <T extends any[]>({
+  apis,
+  children,
+}: TestApiProviderProps<T>) => JSX.Element;
+
+// @public
+export type TestApiProviderProps<TApiPairs extends any[]> = {
+  apis: [...TestApiProviderPropsApiPairs<TApiPairs>];
+  children: ReactNode;
+};
+
 // @public
 export type TestAppOptions = {
   routeEntries?: string[];
diff --git a/packages/test-utils/src/testUtils/TestApiProvider.tsx b/packages/test-utils/src/testUtils/TestApiProvider.tsx
new file mode 100644
index 0000000000..272da8c807
--- /dev/null
+++ b/packages/test-utils/src/testUtils/TestApiProvider.tsx
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import React, { ReactNode } from 'react';
+import { ApiProvider } from '@backstage/core-app-api';
+import { ApiRef, ApiHolder } from '@backstage/core-plugin-api';
+
+type TestApiProviderPropsApiPair<TApi> = TApi extends infer TImpl
+  ? [ApiRef<TApi>, Partial<TImpl>]
+  : never;
+
+/** @ignore */
+type TestApiProviderPropsApiPairs<TApiPairs> = {
+  [TIndex in keyof TApiPairs]: TestApiProviderPropsApiPair<TApiPairs[TIndex]>;
+};
+
+/**
+ * Properties for the {@link TestApiProvider} component.
+ *
+ * @public
+ */
+export type TestApiProviderProps<TApiPairs extends any[]> = {
+  apis: [...TestApiProviderPropsApiPairs<TApiPairs>];
+  children: ReactNode;
+};
+
+/** @internal */
+class TestApiRegistry implements ApiHolder {
+  constructor(private readonly apis: Map<string, unknown>) {}
+
+  get<T>(api: ApiRef<T>): T | undefined {
+    return this.apis.get(api.id) as T | undefined;
+  }
+}
+
+/**
+ * An API provider that lets you provide any number of API implementations in
+ * a test, without necessarily having to implement the full APIs.
+ *
+ * A migration from `ApiRegistry` and `ApiProvider` might look like this, from:
+ *
+ * ```tsx
+ * renderInTestApp(
+ *   <ApiProvider
+ *     apis={ApiRegistry.from([
+ *       [identityApiRef, mockIdentityApi as unknown as IdentityApi]
+ *     ])}
+ *   >
+ *     {...}
+ *   </ApiProvider>
+ * )
+ * ```
+ *
+ * To the following:
+ *
+ * ```tsx
+ * renderInTestApp(
+ *   <TestApiProvider apis={[[identityApiRef, mockIdentityApi]]}>
+ *     {...}
+ *   </TestApiProvider>
+ * )
+ * ```
+ *
+ * Note that the cast to `IdentityApi` is no longer needed as long as the mock API
+ * implements a subset of the `IdentityApi`.
+ *
+ * @public
+ **/
+export const TestApiProvider = <T extends any[]>({
+  apis,
+  children,
+}: TestApiProviderProps<T>) => {
+  return (
+    <ApiProvider
+      apis={
+        new TestApiRegistry(new Map(apis.map(([api, impl]) => [api.id, impl])))
+      }
+      children={children}
+    />
+  );
+};
diff --git a/packages/test-utils/src/testUtils/index.tsx b/packages/test-utils/src/testUtils/index.tsx
index 7d93d606cc..d48767d3cd 100644
--- a/packages/test-utils/src/testUtils/index.tsx
+++ b/packages/test-utils/src/testUtils/index.tsx
@@ -22,3 +22,5 @@ export * from './msw';
 export * from './Keyboard';
 export * from './logCollector';
 export * from './testingLibrary';
+export { TestApiProvider } from './TestApiProvider';
+export type { TestApiProviderProps } from './TestApiProvider';