Merge pull request #307 from gvergnaud/gvergnaud/fix-is-matching-non-objects

fix(isMatching): Fix non-object patterns

Author: gvergnaud

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "ts-pattern",
-  "version": "5.6.1",
+  "version": "5.6.2",
   "description": " The exhaustive Pattern Matching library for TypeScript.",
   "type": "module",
   "source": "src/index.ts",

package.json

@@ -1,12 +1,18 @@
-import {
-  MatchedValue,
-  Pattern,
-  UnknownPattern,
-  UnknownProperties,
-} from './types/Pattern';
+import { MatchedValue, Pattern, UnknownProperties } from './types/Pattern';
 import * as P from './patterns';
 import { matchPattern } from './internals/helpers';
 
+/**
+ * This constraint allows using additional properties
+ * in object patterns. See "should allow targetting unknown properties"
+ * unit test in `is-matching.test.ts`.
+ */
+type PatternConstraint<T> = T extends readonly any[]
+  ? P.Pattern<T>
+  : T extends object
+  ? P.Pattern<T> & UnknownProperties
+  : P.Pattern<T>;
+
 /**
  * `isMatching` takes pattern and returns a **type guard** function, cheching if a value matches this pattern.
  *
@@ -38,10 +44,10 @@ export function isMatching<const p extends Pattern<unknown>>(
  *    return input.name
  *  }
  */
-export function isMatching<
-  const T,
-  const P extends P.Pattern<T> & UnknownProperties
->(pattern: P, value: T): value is P.infer<P>;
+export function isMatching<const T, const P extends PatternConstraint<T>>(
+  pattern: P,
+  value: T
+): value is P.infer<P>;
 
 export function isMatching<const p extends Pattern<any>>(
   ...args: [pattern: p, value?: any]

src/is-matching.ts

@@ -27,6 +27,7 @@ describe('isMatching', () => {
       );
     }
   });
+
   it('should act as a type guard function if given a two arguments', () => {
     const something: unknown = {
       title: 'Hello',
@@ -56,6 +57,47 @@ describe('isMatching', () => {
     }
   });
 
+  it('should work with object patterns', () => {
+    const value: unknown = { foo: true };
+    expect(isMatching({ foo: true }, value)).toEqual(true);
+    expect(isMatching({ foo: 'true' }, value)).toEqual(false);
+  });
+
+  it('should work with array patterns', () => {
+    const value: unknown = [1, 2, 3];
+    expect(isMatching(P.array(P.number), value)).toEqual(true);
+    expect(isMatching(P.array(P.string), value)).toEqual(false);
+  });
+
+  it('should work with variadic patterns', () => {
+    const value: unknown = [1, 2, 3];
+    expect(isMatching([1, ...P.array(P.number)], value)).toEqual(true);
+    expect(isMatching([2, ...P.array(P.number)], value)).toEqual(false);
+  });
+
+  it('should work with primitive patterns', () => {
+    const value: unknown = 1;
+    expect(isMatching(P.number, value)).toEqual(true);
+    expect(isMatching(P.boolean, value)).toEqual(false);
+  });
+
+  it('should work with literal patterns', () => {
+    const value: unknown = 1;
+    expect(isMatching(1, value)).toEqual(true);
+    expect(isMatching('oops', value)).toEqual(false);
+  });
+
+  it('should work with union and intersection patterns', () => {
+    const value: unknown = { foo: true };
+    expect(isMatching(P.union({ foo: true }, { bar: false }), value)).toEqual(
+      true
+    );
+
+    expect(isMatching(P.union({ foo: false }, { bar: false }), value)).toEqual(
+      false
+    );
+  });
+
   type Pizza = { type: 'pizza'; topping: string };
   type Sandwich = { type: 'sandwich'; condiments: string[] };
   type Food = Pizza | Sandwich;
@@ -83,7 +125,9 @@ describe('isMatching', () => {
 
     isMatching(
       // @ts-expect-error
-      { type: 'oops' },
+      {
+        type: 'oops',
+      },
       food
     );
   });