Add a bit hacky error to throw instead of full powered AssertionError

lib/assertion.js

@@ -6,6 +6,30 @@
  */
 
 import AssertionError from './assertion-error';
+import { merge } from 'should-util';
+
+
+// a bit hacky way how to get error to do not have stack
+function LightAssertionError(options) {
+  merge(this, options);
+
+  if (!options.message) {
+    Object.defineProperty(this, 'message', {
+      get: function() {
+        if (!this._message) {
+          this._message = this.generateMessage();
+          this.generatedMessage = true;
+        }
+        return this._message;
+      }
+    });
+  }
+}
+
+LightAssertionError.prototype = {
+  generateMessage: AssertionError.prototype.generateMessage
+};
+
 
 /**
  * should Assertion
@@ -69,7 +93,11 @@ Assertion.prototype = {
 
     params.assertion = this;
 
-    throw new AssertionError(params);
+    if (this.light) {
+      throw new LightAssertionError(params);
+    } else {
+      throw new AssertionError(params);
+    }
   },
 
   /**
@@ -142,12 +170,13 @@ Assertion.add = function(name, func) {
     value: function() {
       var context = new Assertion(this.obj, this, name);
       context.anyOne = this.anyOne;
+      context.light = true;
 
       try {
         func.apply(context, arguments);
       } catch (e) {
         // check for fail
-        if (e instanceof AssertionError) {
+        if (e instanceof AssertionError || e instanceof LightAssertionError) {
           // negative fail
           if (this.negate) {
             this.obj = context.obj;
@@ -161,6 +190,7 @@ Assertion.add = function(name, func) {
 
           // positive fail
           context.negate = false;
+          context.light = false;
           context.fail();
         }
         // throw if it is another exception
@@ -171,6 +201,7 @@ Assertion.add = function(name, func) {
       if (this.negate) {
         context.negate = true; // because .fail will set negate
         context.params.details = 'false negative fail';
+        context.light = false;
         context.fail();
       }
 

test/not.test.js

@@ -0,0 +1,28 @@
+var should = require('../');
+var err = require('./util').err;
+
+
+var a = 10;
+var b = 11;
+
+describe('.not', function() {
+  it('should not throw when true', function() {
+    a.should.be.exactly(a);
+  });
+
+  it('should throw when false', function() {
+    err(function() {
+      a.should.be.exactly(b);
+    }, 'expected 10 to be 11');
+  });
+
+  it('should throw when not true (false negative case)', function() {
+    err(function() {
+      a.should.not.be.exactly(a);
+    }, 'expected 10 not to be 10 (false negative fail)');
+  });
+
+  it('should not throw when not false', function() {
+    a.should.not.be.exactly(b);
+  });
+});