augment the error

lib/versioned/^4.0.0/index.js

@@ -12,8 +12,8 @@ var tildify = require('../../shared/tildify');
 var logTasks = require('../../shared/log/tasks');
 var logEvents = require('./log/events');
 var logSyncTask = require('./log/sync-task');
+var normalizeError = require('./normalize-error');
 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');
@@ -86,13 +86,12 @@ function execute(env, cfg, opts) {
         }
       });
     } catch (err) {
-      var task = checkTaskNotFound(err);
-      if (task) {
+      normalizeError(err);
+      if (err.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/normalize-error.js

@@ -0,0 +1,26 @@
+'use strict';
+
+// Normalize an undertaker v1 error like an undertaker v2 error
+function normalizeError(err) {
+  /* istanbul ignore if */
+  if (!err || !err.message) {
+    return;
+  }
+
+  var fixed0 = 'Task never defined: ';
+  var fixed1 = ' - did you mean? ';
+
+  if (err.message.startsWith(fixed0)) {
+    var task = err.message.slice(fixed0.length);
+    var index = task.indexOf(fixed1);
+
+    if (index >= 0) {
+      err.similar = task.slice(index + fixed1.length).split(', ');
+      err.task = task.slice(0, index);
+    } else {
+      err.task = task
+    }
+  }
+}
+
+module.exports = normalizeError;

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

@@ -1,28 +1,31 @@
 'use strict';
 
 var expect = require('expect');
-var checkTaskNotFound = require('../../lib/versioned/^4.0.0/log/check-task-not-found');
+var normalizeError = require('../../lib/versioned/^4.0.0/normalize-error');
 
-describe('lib: checkTaskNotFound', function() {
+describe('lib: normalizeError', 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']
-    });
+    normalizeError(err);
+    expect(err).toHaveProperty('task', 'task2');
+    expect(err).toHaveProperty('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' });
+    normalizeError(err)
+    expect(err).toHaveProperty('task', 'task2');
+    expect(err).not.toHaveProperty('similar');
     done();
   });
 
   it('Should return undefined if error is other', function(done) {
     var err = new Error('xxx');
-    expect(checkTaskNotFound(err)).toBeUndefined();
+    normalizeError(err)
+    expect(err).not.toHaveProperty('task');
+    expect(err).not.toHaveProperty('similar');
     done();
   });
 });