packages/core-api: added .with() as another way to construct ApiRegistries

packages/core-api/src/apis/ApiRegistry.test.ts

@@ -49,4 +49,20 @@ describe('ApiRegistry', () => {
     expect(registry.get(x1Ref)).toBe(3);
     expect(registry.get(x2Ref)).toBe('y');
   });
+
+  it('should be created with API', () => {
+    const reg1 = ApiRegistry.with(x1Ref, 3);
+    const reg2 = reg1.with(x2Ref, 'y');
+    const reg3 = reg2.with(x2Ref, 'z');
+    const reg4 = reg3.with(x1Ref, 2);
+
+    expect(reg1.get(x1Ref)).toBe(3);
+    expect(reg1.get(x2Ref)).toBe(undefined);
+    expect(reg2.get(x1Ref)).toBe(3);
+    expect(reg2.get(x2Ref)).toBe('y');
+    expect(reg3.get(x1Ref)).toBe(3);
+    expect(reg3.get(x2Ref)).toBe('z');
+    expect(reg4.get(x1Ref)).toBe(2);
+    expect(reg4.get(x2Ref)).toBe('z');
+  });
 });

packages/core-api/src/apis/ApiRegistry.ts

@@ -42,8 +42,28 @@ export class ApiRegistry implements ApiHolder {
     return new ApiRegistry(new Map(apis));
   }
 
+  /**
+   * Creates a new ApiRegistry with a single API implementation.
+   *
+   * @param api ApiRef for the API to add
+   * @param impl Implementation of the API to add
+   */
+  static with<T>(api: ApiRef<T>, impl: T): ApiRegistry {
+    return new ApiRegistry(new Map([[api, impl]]));
+  }
+
   constructor(private readonly apis: Map<ApiRef<unknown>, unknown>) {}
 
+  /**
+   * Returns a new ApiRegistry with the provided API added to the existing ones.
+   *
+   * @param api ApiRef for the API to add
+   * @param impl Implementation of the API to add
+   */
+  with<T>(api: ApiRef<T>, impl: T): ApiRegistry {
+    return new ApiRegistry(new Map([...this.apis, [api, impl]]));
+  }
+
   get<T>(api: ApiRef<T>): T | undefined {
     return this.apis.get(api) as T | undefined;
   }