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

ts/smartexpect.classes.assertion.ts

@@ -18,6 +18,14 @@ import type { TMatcher, TExecutionType } from './types.js';
 /**
  * Core assertion class. Generic over the current value type T.
  */
+/**
+ * Internal matcher classes for expect.any and expect.anything
+ */
+export class AnyMatcher {
+  constructor(public expectedConstructor: any) {}
+}
+export class AnythingMatcher {}
+
 export class Assertion<T = unknown> {
   executionMode: TExecutionType;
   baseReference: any;
@@ -33,6 +41,8 @@ export class Assertion<T = unknown> {
   private isResolves = false;
   private failMessage: string;
   private successMessage: string;
+  /** Computed negation failure message for the current assertion */
+  private negativeMessage: string;
 
   constructor(baseReferenceArg: any, executionModeArg: TExecutionType) {
     this.baseReference = baseReferenceArg;
@@ -131,6 +141,16 @@ export class Assertion<T = unknown> {
       .replace('{value}', formattedValue)
       .replace('{path}', drillDown || '');
   }
+  /**
+   * Compute a negated failure message by inserting 'not' into the positive message.
+   */
+  private computeNegationMessage(message: string): string {
+    const idx = message.indexOf(' to ');
+    if (idx !== -1) {
+      return message.slice(0, idx) + ' not' + message.slice(idx);
+    }
+    return 'Negated: ' + message;
+  }
 
   public get not() {
     this.notSetting = true;
@@ -190,12 +210,14 @@ export class Assertion<T = unknown> {
       } else {
         let isOk = false;
         try {
-          runDirectOrNegated(checkFunction());
+        // attempt positive assertion and expect it to throw
+        checkFunction();
         } catch (e) {
           isOk = true;
         }
         if (!isOk) {
-          throw new Error(this.failMessage || 'Negated assertion failed');
+          const msg = this.failMessage || this.negativeMessage || 'Negated assertion failed';
+          throw new Error(msg);
         }
       }
     };
@@ -252,12 +274,18 @@ export class Assertion<T = unknown> {
 
   public customAssertion(
     assertionFunction: (value: any) => boolean,
-    errorMessage: string
+    errorMessage: string | ((value: any) => string)
   ) {
+    // Prepare negation message based on the positive error template, if static
+    if (typeof errorMessage === 'string') {
+      this.negativeMessage = this.computeNegationMessage(errorMessage);
+    }
     return this.runCheck(() => {
       const value = this.getObjectToTestReference();
       if (!assertionFunction(value)) {
-        throw new Error(this.failMessage || errorMessage);
+        const msg = this.failMessage
+          || (typeof errorMessage === 'function' ? errorMessage(value) : errorMessage);
+        throw new Error(msg);
       }
     });
   }