feat(util-dev): add patchObject test util

Author: mkazlauskas

packages/util-dev/src/index.ts

@@ -12,3 +12,4 @@ export * from './createStubUtxoProvider';
 export * from './createGenericMockServer';
 export * from './dataGeneration';
 export * from './eraSummaries';
+export * from './patchObject';

packages/util-dev/src/patchObject.ts

@@ -0,0 +1,7 @@
+export const patchObject = <T extends object>(baseObject: T, patches: Partial<T>) =>
+  new Proxy(baseObject, {
+    get(target, p, receiver) {
+      const value = p in patches ? patches[p as keyof T] : target[p as keyof T];
+      return typeof value === 'function' ? value.bind(receiver) : value;
+    }
+  });

packages/util-dev/test/patchObject.test.ts

@@ -0,0 +1,26 @@
+import { patchObject } from '../src';
+
+describe('patchObject', () => {
+  const object = {
+    fnKey() {
+      return this.key;
+    },
+    key: {}
+  };
+
+  it('preserves unpatched base object properties', () => {
+    const patchedObject = patchObject(object, {});
+    expect(patchedObject.key).toBe(object.key);
+    expect(patchedObject.fnKey()).toBe(object.fnKey());
+  });
+
+  it('overrides patched properties', () => {
+    const patchedKey = {};
+    const patchedObject = patchObject(object, {
+      key: patchedKey
+    });
+    expect(patchedObject.key).toBe(patchedKey);
+    expect(patchedObject.key).not.toBe(object.key);
+    expect(patchedObject.fnKey()).toBe(patchedKey);
+  });
+});