Displays a message without a stack trace for ambiguous commands

Author: Srihari Sriraman

lib/thor.rb

@@ -421,7 +421,7 @@ def normalize_command_name(meth) #:nodoc:
 
       possibilities = find_command_possibilities(meth)
       if possibilities.size > 1
-        raise ArgumentError, "Ambiguous command #{meth} matches [#{possibilities.join(', ')}]"
+        raise AmbiguousTaskError, "Ambiguous command #{meth} matches [#{possibilities.join(', ')}]"
       elsif possibilities.size < 1
         meth = meth || default_command
       elsif map[meth]

lib/thor/error.rb

@@ -13,6 +13,10 @@ class UndefinedCommandError < Error
   end
   UndefinedTaskError = UndefinedCommandError
 
+  class AmbiguousCommandError < Error
+  end
+  AmbiguousTaskError = AmbiguousCommandError
+
   # Raised when a command was found, but not invoked properly.
   class InvocationError < Error
   end

spec/thor_spec.rb

@@ -303,12 +303,16 @@ def boring(*args)
     end
 
     context "when the user enters an ambiguous substring of a command" do
-      it "raises an exception that explains the ambiguity" do
-        expect{ MyScript.start(["call"]) }.to raise_error(ArgumentError, 'Ambiguous command call matches [call_myself_with_wrong_arity, call_unexistent_method]')
+      it "raises an exception and displays a message that explains the ambiguity" do
+        shell = Thor::Base.shell.new
+        expect(shell).to receive(:error).with('Ambiguous command call matches [call_myself_with_wrong_arity, call_unexistent_method]')
+        MyScript.start(["call"], :shell => shell)
       end
 
       it "raises an exception when there is an alias" do
-        expect{ MyScript.start(["f"]) }.to raise_error(ArgumentError, 'Ambiguous command f matches [foo, fu]')
+        shell = Thor::Base.shell.new
+        expect(shell).to receive(:error).with('Ambiguous command f matches [foo, fu]')
+        MyScript.start(["f"], :shell => shell)
       end
     end