feat(core): Add new matchers and improve negation messaging

ts/namespaces/function.ts

@@ -26,4 +26,36 @@ export class FunctionMatchers {
       `Expected function to throw${expectedError ? ` ${expectedError}` : ''}`
     );
   }
+  /**
+   * Assert thrown error message matches the given regex
+   */
+  toThrowErrorMatching(regex: RegExp) {
+    return this.assertion.customAssertion(
+      (value) => {
+        try {
+          (value as Function)();
+        } catch (e: any) {
+          return regex.test(e && e.message);
+        }
+        return false;
+      },
+      `Expected function to throw error matching ${regex}`
+    );
+  }
+  /**
+   * Assert thrown error message equals the given string
+   */
+  toThrowErrorWithMessage(expectedMessage: string) {
+    return this.assertion.customAssertion(
+      (value) => {
+        try {
+          (value as Function)();
+        } catch (e: any) {
+          return e && e.message === expectedMessage;
+        }
+        return false;
+      },
+      `Expected function to throw error with message "${expectedMessage}"`
+    );
+  }
 }