From 349e1ef4f122275053450b4add0269b33e7f5185 Mon Sep 17 00:00:00 2001
From: Daniel Berger <djberg96@gmail.com>
Date: Fri, 9 Jan 2015 17:52:39 -0700
Subject: [PATCH 1/2] Modify output on failed task to offer alternatives.

---
 lib/rake/task_manager.rb | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/lib/rake/task_manager.rb b/lib/rake/task_manager.rb
index cbb9f5ee2..b4ff71b9b 100644
--- a/lib/rake/task_manager.rb
+++ b/lib/rake/task_manager.rb
@@ -59,7 +59,20 @@ def [](task_name, scopes=nil)
       self.lookup(task_name, scopes) or
         enhance_with_matching_rule(task_name) or
         synthesize_file_task(task_name) or
-        fail "Don't know how to build task '#{task_name}'"
+        build_task_fail(task_name)
+    end
+
+    # If a task match wasn't found, try to offer suggestions.
+    # The task name must be at least 2 characters.
+    def build_task_fail(task_name)
+      msg = "Don't know how to build task '#{task_name}'"
+      if task_name.size > 1
+        matches = @tasks.keys.find_all{ |e| e =~ /#{task_name}/i }
+        if matches.size > 0
+          msg += ". Did you mean one of these?\n\n" + matches.map{ |e| "  #{e}" }.join("\n") + "\n"
+        end
+      end
+      fail msg
     end
 
     def synthesize_file_task(task_name) # :nodoc:

From 4b248af56ad207418a92f12f53576a1dca5d1f38 Mon Sep 17 00:00:00 2001
From: Daniel Berger <djberg96@gmail.com>
Date: Fri, 9 Jan 2015 19:03:08 -0700
Subject: [PATCH 2/2] Added test for alt suggestions.

---
 test/test_rake_task.rb | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/test/test_rake_task.rb b/test/test_rake_task.rb
index 0416dfa8d..c72643909 100644
--- a/test/test_rake_task.rb
+++ b/test/test_rake_task.rb
@@ -148,6 +148,15 @@ def test_find
     assert_equal "Don't know how to build task 'leaves'", ex.message
   end
 
+  def test_find_with_alts
+    task :tfindx
+    assert_equal "tfindx", Task[:tfindx].name
+    ex = assert_raises(RuntimeError) { Task[:tfind] }
+    assert_match /Don\'t know how to build task \'tfind\'/, ex.message
+    assert_match /Did you mean one of these\?/, ex.message
+    assert_match /tfindx/, ex.message
+  end
+
   def test_defined
     assert ! Task.task_defined?(:a)
     task :a