feat: 'toBeFalse' expectation

src/Expect.ts

@@ -12,6 +12,18 @@ export function toBeTrue(condition: boolean, errorMessage?: string) {
     }
 }
 
+/**
+ * Expect that a condition is false.
+ * @param condition The condition expected to be false.
+ * @param errorMessage The optional error message displayed if expectation fails.
+ * @throws {ExpectationError}
+ */
+export function toBeFalse(condition: boolean, errorMessage?: string) {
+    if (condition) {
+        throw new ExpectationError(errorMessage);
+    }
+}
+
 /**
  * Expect that a value exists.
  * @param value The value expected to exist.

test/Expect.spec.ts

@@ -19,6 +19,16 @@ describe('expect', () => {
         });
     });
 
+    describe('#toBeFalse', () => {
+        it('should pass if expectation is fulfilled', () => {
+            expect.toBeFalse(false);
+        });
+
+        it('should fail if expectation is unfulfilled', () => {
+            (() => expect.toBeFalse(true, errorMessage)).should.throw(ExpectationError).with.property('message', errorMessage);
+        });
+    });
+
     describe('#toExist', () => {
         it('should pass if expectation is fulfilled', () => {
             expect.toExist(true);