Rethrow the compilation error after printing the message.

Gruntfile.js

@@ -226,12 +226,24 @@ module.exports = function(grunt) {
       }
     },
 
+    less_error: {
+      error: {
+        files: {
+          'tmp/invalid.css': ['test/fixtures/invalid.less']
+        }
+      },
+    },
+
     // Unit tests.
     nodeunit: {
       tests: ['test/*_test.js']
     }
   });
 
+  // First load this plugin's task(s) and rename for testing errors.
+  grunt.loadTasks('tasks');
+  grunt.renameTask('less', 'less_error');
+
   // Actually load this plugin's task(s).
   grunt.loadTasks('tasks');
 

tasks/less.js

@@ -164,6 +164,7 @@ module.exports = function(grunt) {
     return less.render(srcCode, options)
       .catch(function(err) {
         lessError(err, srcFile);
+        throw err;
       });
   };
 

test/fixtures/invalid.less

@@ -0,0 +1,2 @@
+.invalid {
+  missing: brace;

test/less_test.js

@@ -34,6 +34,23 @@ exports.less = {
 
     test.done();
   },
+  invalid: function(test) {
+    test.expect(4);
+
+    grunt.util.spawn({
+      grunt: true,
+      args: ['--force', 'less_error:error']
+    }, function doneFunction(error, result, code) {
+      test.equal(error, null, 'Error should be null');
+      test.equal(code, 0, 'the code should be 0');
+      test.ok(
+        /ParseError: Unrecognised input\./.test(result.stdout),
+        'The result should contain error info.');
+      test.ok(/\bDone\b/.test(result.stdout), 'The result should contain the "Done" word');
+
+      test.done();
+    });
+  },
   nopaths: function(test) {
     test.expect(1);