feat(expect): added null as positive value for toBeOptionalOf

packages/expect-more-jest/src/to-be-optional-of.ts

@@ -1,4 +1,4 @@
-import { isUndefined } from 'expect-more';
+import { isUndefined, isNull } from 'expect-more';
 import { equals } from 'expect/build/jasmineUtils';
 import { printExpected, printReceived } from 'jest-matcher-utils';
 import { createResult } from './lib/create-result';
@@ -7,7 +7,7 @@ declare global {
   namespace jest {
     interface Matchers<R> {
       /**
-       * Asserts that a value is equal to ${other} or undefined.
+       * Asserts that a value is equal to ${other} or undefined or null.
        * @example
        * expect({ x: 12, y: 22 }).toBeOptionalOf({
        *   x: expect.toBeNumber(),
@@ -17,12 +17,16 @@ declare global {
        *   x: expect.toBeNumber(),
        *   y: expect.toBeNumber(),
        * });
+       * expect(null).toBeOptionalOf({
+       *   x: expect.toBeNumber(),
+       *   y: expect.toBeNumber(),
+       * });
        */
       toBeOptionalOf(other: unknown): R;
     }
     interface Expect {
       /**
-       * Asserts that a value is equal to ${other} or undefined.
+       * Asserts that a value is equal to ${other} or undefined or null.
        * @example
        * expect({ x: 12, y: 22 }).toEqual(
        *   expect.toBeOptionalOf({
@@ -36,6 +40,10 @@ declare global {
        *     y: expect.toBeNumber()
        *   })
        * );
+       * expect(null).toBeOptionalOf({
+       *   x: expect.toBeNumber(),
+       *   y: expect.toBeNumber(),
+       * });
        */
       toBeOptionalOf<T>(other: unknown): JestMatchers<T>;
     }
@@ -47,12 +55,12 @@ export const toBeOptionalOfMatcher = (value: unknown, other: unknown): jest.Cust
     message: () =>
       `expected ${printReceived(value)} to equal ${printExpected(other)} or ${printExpected(
         undefined,
-      )}`,
+      )} or ${printExpected(null)}`,
     notMessage: () =>
       `expected ${printReceived(value)} not to equal ${printExpected(other)} or ${printExpected(
         undefined,
-      )}`,
-    pass: isUndefined(value) || equals(value, other),
+      )} or ${printExpected(null)}`,
+    pass: isUndefined(value) || isNull(value) || equals(value, other),
   });
 
 expect.extend({ toBeOptionalOf: toBeOptionalOfMatcher });

packages/expect-more-jest/test/to-be-optional-of.spec.ts

@@ -8,6 +8,7 @@ const expectedShape = {
 it('provides expect().toBeOptionalOf()', () => {
   expect({ x: 0, y: 12 }).toBeOptionalOf(expectedShape);
   expect(undefined).toBeOptionalOf(expectedShape);
+  expect(null).toBeOptionalOf(expectedShape);
 });
 
 it('provides expect().not.toBeOptionalOf()', () => {