fix: component setter is overwritten when component properties are set (#192)

Closes #191

Author: GlebIrovich

apps/example-app/app/examples/16-input-getter-setter.spec.ts

@@ -0,0 +1,25 @@
+import { render, screen } from '@testing-library/angular';
+import { InputGetterSetter } from './16-input-getter-setter';
+
+test('should run logic in the input setter and getter', async () => {
+  await render(InputGetterSetter, { componentProperties: { value: 'Angular' } });
+  const valueControl = screen.getByTestId('value');
+  const getterValueControl = screen.getByTestId('value-getter');
+
+  expect(valueControl.textContent).toBe('I am value from setter Angular');
+  expect(getterValueControl.textContent).toBe('I am value from getter Angular');
+});
+
+test('should run logic in the input setter and getter while re-rendering', async () => {
+  const component = await render(InputGetterSetter, { componentProperties: { value: 'Angular' } });
+  const valueControl = screen.getByTestId('value');
+  const getterValueControl = screen.getByTestId('value-getter');
+
+  expect(valueControl.textContent).toBe('I am value from setter Angular');
+  expect(getterValueControl.textContent).toBe('I am value from getter Angular');
+
+  await component.rerender({ value: 'React' });
+
+  expect(valueControl.textContent).toBe('I am value from setter React');
+  expect(getterValueControl.textContent).toBe('I am value from getter React');
+});

apps/example-app/app/examples/16-input-getter-setter.ts

@@ -0,0 +1,22 @@
+import { Component, Input } from '@angular/core';
+
+@Component({
+  selector: 'app-fixture',
+  template: `
+    <span data-testid="value">{{ derivedValue }}</span>
+    <span data-testid="value-getter">{{ value }}</span>
+  `,
+})
+export class InputGetterSetter {
+  @Input() set value(value: string) {
+    this.originalValue = value;
+    this.derivedValue = 'I am value from setter ' + value;
+  }
+
+  get value() {
+    return 'I am value from getter ' + this.originalValue;
+  }
+
+  private originalValue: string;
+  derivedValue: string;
+}

projects/testing-library/src/lib/testing-library.ts

@@ -205,14 +205,24 @@ function setComponentProperties<SutType>(
   { componentProperties = {} }: Pick<RenderDirectiveOptions<SutType, any>, 'componentProperties'>,
 ) {
   for (const key of Object.keys(componentProperties)) {
+    const descriptor: PropertyDescriptor = Object.getOwnPropertyDescriptor(
+      fixture.componentInstance.constructor.prototype,
+      key,
+    );
     let _value = componentProperties[key];
+    const defaultGetter = () => _value;
+    const extendedSetter = (value) => {
+      _value = value;
+      descriptor?.set?.call(fixture.componentInstance, _value);
+      fixture.detectChanges();
+    };
+
     Object.defineProperty(fixture.componentInstance, key, {
-      get: () => _value,
-      set: (value) => {
-        _value = value;
-        fixture.detectChanges();
-      },
+      get: descriptor?.get || defaultGetter,
+      set: extendedSetter,
     });
+
+    descriptor?.set?.call(fixture.componentInstance, _value);
   }
   return fixture;
 }