update: separate error while running gulpfile into task not found a…

…nd `fail to run`

lib/versioned/^4.0.0/index.js

@@ -13,6 +13,7 @@ var logTasks = require('../../shared/log/tasks');
 var logEvents = require('./log/events');
 var logSyncTask = require('./log/sync-task');
 var logTasksSimple = require('./log/tasks-simple');
+var checkTaskNotFound = require('./log/check-task-not-found');
 var registerExports = require('../../shared/register-exports');
 
 var copyTree = require('../../shared/log/copy-tree');
@@ -85,8 +86,14 @@ function execute(env, cfg, opts) {
         }
       });
     } catch (err) {
-      log.error(chalk.red(err.message));
-      log.error('To list available tasks, try running: gulp --tasks');
+      var task = checkTaskNotFound(err);
+      if (task) {
+        log.error(chalk.red(err.message));
+        log.error(chalk.red('To list available tasks, try running: gulp --tasks'));
+      } else /* istanbul ignore next */ {
+        log.error(chalk.red(err.message));
+        log.error('Please check the documentation for proper gulpfile formatting');
+      }
       exit(1);
     }
   });

lib/versioned/^4.0.0/log/check-task-not-found.js

@@ -0,0 +1,29 @@
+'use strict';
+
+function checkTaskNotFound(err) {
+  /* istanbul ignore if */
+  if (!err || !err.message) {
+    return undefined;
+  }
+  var fixed0 = 'Task never defined: ';
+  var fixed1 = ' - did you mean? ';
+
+  if (err.message.startsWith(fixed0)) {
+    var target = err.message.slice(fixed0.length);
+    var similar = undefined;
+
+    var index = target.indexOf(fixed1);
+    if (index >= 0) {
+      similar = target.slice(index + fixed1.length).split(', ');
+      target = target.slice(0, index);
+    }
+
+    if (similar && similar.length) {
+      return { target: target, similar: similar };
+    } else {
+      return { target: target };
+    }
+  }
+}
+
+module.exports = checkTaskNotFound;

test/execution-errors.js

@@ -29,6 +29,21 @@ describe('execution error', function() {
     }
   });
 
+  it('should output an error if a task is not defined but a similar task is found', function(done) {
+    var opts = { cwd: path.join(__dirname, './fixtures/gulpfiles') };
+    exec(gulp('test0'), opts, cb);
+
+    function cb(err, stdout, stderr) {
+      expect(err).not.toBeNull();
+      expect(err.code).toEqual(1);
+      expect(eraseTime(stdout)).toMatch('Using gulpfile ');
+      expect(eraseTime(stderr)).toEqual(
+        'Task never defined: test0 - did you mean? test1, test2, test3, test4, test5, test6, test7, test8\n' +
+        'To list available tasks, try running: gulp --tasks\n');
+      done();
+    }
+  });
+
   it('should output an error if gulp version is unsupported', function(done) {
     var opts = { cwd: path.join(__dirname, './fixtures/errors/bad-gulp-version') };
     exec(gulp(), opts, cb);

test/lib/check-task-not-found.js

@@ -0,0 +1,28 @@
+'use strict';
+
+var expect = require('expect');
+var checkTaskNotFound = require('../../lib/versioned/^4.0.0/log/check-task-not-found');
+
+describe('lib: checkTaskNotFound', function() {
+
+  it('Should return target task and similar tasks if both are included in error message', function(done) {
+    var err = new Error('Task never defined: task2 - did you mean? task0, task1');
+    expect(checkTaskNotFound(err)).toEqual({
+      target: 'task2',
+      similar: ['task0', 'task1']
+    });
+    done();
+  });
+
+  it('Should return only target task if similar tasks is not included in error message', function(done) {
+    var err = new Error('Task never defined: task2');
+    expect(checkTaskNotFound(err)).toEqual({ target: 'task2' });
+    done();
+  });
+
+  it('Should return undefined if error is other', function(done) {
+    var err = new Error('xxx');
+    expect(checkTaskNotFound(err)).toBeUndefined();
+    done();
+  });
+});