feat: Console output test util (#1370)

Console output test util

resolves #1369

Author: bmingles

packages/utils/src/TestUtils.test.tsx

@@ -2,7 +2,7 @@ import React from 'react';
 import { render, screen } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 
-import TestUtils from './TestUtils';
+import TestUtils, { ConsoleMethodName } from './TestUtils';
 import createMockProxy from './MockProxy';
 
 beforeEach(() => {
@@ -19,6 +19,42 @@ describe('asMock', () => {
   expect(someFunc('a,b,c')).toEqual(3);
 });
 
+/* eslint-disable no-console */
+describe('disableConsoleOutput', () => {
+  const arg0 = 'mock arg';
+  const allMethodNames = Object.getOwnPropertyNames(console).filter(
+    (name): name is ConsoleMethodName =>
+      typeof console[name as keyof Console] === 'function'
+  );
+
+  it('should disable all methods if given no method names', () => {
+    TestUtils.disableConsoleOutput();
+
+    allMethodNames.forEach(methodName => {
+      console[methodName]();
+
+      expect(console[methodName]).toHaveBeenCalled();
+    });
+  });
+
+  it.each([
+    [['log']],
+    [['warn']],
+    [['error']],
+    [['info']],
+    [['debug']],
+    [allMethodNames],
+  ] as const)('should mock console method implementations: %s', methodNames => {
+    TestUtils.disableConsoleOutput(...methodNames);
+
+    methodNames.forEach(methodName => {
+      console[methodName](arg0);
+      expect(console[methodName]).toHaveBeenCalledWith(arg0);
+    });
+  });
+});
+/* eslint-enable no-console */
+
 describe('findLastCall', () => {
   it('should return undefined if call not matched', () => {
     const fn = jest.fn<void, [string, number]>();

packages/utils/src/TestUtils.ts

@@ -31,6 +31,17 @@ export interface ClickOptions {
   rightClick?: boolean;
 }
 
+/**
+ * Filters a type down to only method properties.
+ */
+export type PickMethods<T> = {
+  [K in keyof T as T[K] extends (...args: unknown[]) => unknown
+    ? K
+    : never]: T[K];
+};
+
+export type ConsoleMethodName = keyof PickMethods<Console>;
+
 class TestUtils {
   /**
    * Type assertion to "cast" a function to it's corresponding jest.Mock
@@ -52,6 +63,27 @@ class TestUtils {
     fn: (...args: TArgs) => TResult
   ): jest.Mock<TResult, TArgs> => (fn as unknown) as jest.Mock<TResult, TArgs>;
 
+  /**
+   * Selectively disable logging methods on `console` object. Uses spyOn so that
+   * changes will be reverted after leaving the test scope that it is set in. If
+   * no method names are given, all will be disabled.
+   * @param methodNames The console methods to disable.
+   */
+  static disableConsoleOutput = (...methodNames: ConsoleMethodName[]): void => {
+    if (methodNames.length === 0) {
+      // eslint-disable-next-line no-param-reassign
+      methodNames = Object.getOwnPropertyNames(console).filter(
+        (name): name is ConsoleMethodName =>
+          // eslint-disable-next-line no-console
+          typeof console[name as keyof Console] === 'function'
+      );
+    }
+
+    methodNames.forEach(methodName => {
+      jest.spyOn(console, methodName).mockImplementation();
+    });
+  };
+
   /**
    * Find the last mock function call matching a given predicate.
    * @param fn jest.Mock function