feat(utils): implement type guard for nullable object props

Author: matejchalk

packages/plugin-lighthouse/src/lib/types.ts

@@ -1,7 +1,7 @@
 import type { CliFlags } from 'lighthouse';
-import type { ExcludeNullFromPropertyTypes } from '@code-pushup/utils';
+import type { ExcludeNullableProps } from '@code-pushup/utils';
 
-export type LighthouseOptions = ExcludeNullFromPropertyTypes<
+export type LighthouseOptions = ExcludeNullableProps<
   Partial<
     Omit<
       CliFlags,

packages/utils/src/index.ts

@@ -39,13 +39,6 @@ export {
   truncateText,
   truncateTitle,
 } from './lib/formatting.js';
-export {
-  formatGitPath,
-  getGitRoot,
-  guardAgainstLocalChanges,
-  safeCheckout,
-  toGitPath,
-} from './lib/git/git.js';
 export {
   getCurrentBranchOrTag,
   getHashFromTag,
@@ -54,10 +47,18 @@ export {
   getSemverTags,
   type LogResult,
 } from './lib/git/git.commits-and-tags.js';
+export {
+  formatGitPath,
+  getGitRoot,
+  guardAgainstLocalChanges,
+  safeCheckout,
+  toGitPath,
+} from './lib/git/git.js';
 export { groupByStatus } from './lib/group-by-status.js';
 export {
   isPromiseFulfilledResult,
   isPromiseRejectedResult,
+  hasNoNullableProps,
 } from './lib/guards.js';
 export { logMultipleResults } from './lib/log-results.js';
 export { link, ui, type CliUi, type Column } from './lib/logging.js';
@@ -114,7 +115,7 @@ export {
   type CliArgsObject,
 } from './lib/transform.js';
 export type {
-  ExcludeNullFromPropertyTypes,
+  ExcludeNullableProps,
   ExtractArray,
   ExtractArrays,
   ItemOrArray,

packages/utils/src/lib/guards.ts

@@ -1,3 +1,5 @@
+import type { ExcludeNullableProps } from './types.js';
+
 export function isPromiseFulfilledResult<T>(
   result: PromiseSettledResult<T>,
 ): result is PromiseFulfilledResult<T> {
@@ -9,3 +11,9 @@ export function isPromiseRejectedResult(
 ): result is PromiseRejectedResult {
   return result.status === 'rejected';
 }
+
+export function hasNoNullableProps<T extends object>(
+  obj: T,
+): obj is ExcludeNullableProps<T> {
+  return Object.values(obj).every(value => value != null);
+}

packages/utils/src/lib/guards.unit.test.ts

@@ -1,5 +1,9 @@
 import { describe } from 'vitest';
-import { isPromiseFulfilledResult, isPromiseRejectedResult } from './guards.js';
+import {
+  hasNoNullableProps,
+  isPromiseFulfilledResult,
+  isPromiseRejectedResult,
+} from './guards.js';
 
 describe('promise-result', () => {
   it('should get fulfilled result', () => {
@@ -20,3 +24,21 @@ describe('promise-result', () => {
     expect(isPromiseRejectedResult(result)).toBe(true);
   });
 });
+
+describe('hasNoNullableProps', () => {
+  it('should return true if object prop values are neither null nor undefined', () => {
+    expect(hasNoNullableProps({ a: 42, b: 'foo', c: {}, d: [] })).toBe(true);
+  });
+
+  it('should return false if some prop is null', () => {
+    expect(hasNoNullableProps({ x: 42, y: null })).toBe(false);
+  });
+
+  it('should return false if some prop is set to undefined', () => {
+    expect(hasNoNullableProps({ x: undefined })).toBe(false);
+  });
+
+  it('should return true for empty object', () => {
+    expect(hasNoNullableProps({})).toBe(true);
+  });
+});

packages/utils/src/lib/types.ts

@@ -1,5 +1,5 @@
-export type ExcludeNullFromPropertyTypes<T> = {
-  [P in keyof T]: Exclude<T[P], null>;
+export type ExcludeNullableProps<T> = {
+  [P in keyof T]: NonNullable<T[P]>;
 };
 
 export type ItemOrArray<T> = T | T[];