Search: Present a user friendly message with invalid regex

Fixes #1821

CHANGELOG.md

@@ -13,6 +13,10 @@ To install or update CocoaPods see this [guide](http://docs.cocoapods.org/guides
   [Jeff Verkoeyen](https://github.com/jverkoey)
   [#1803](https://github.com/CocoaPods/CocoaPods/pull/1803)
 
+* Improves the error message when searching with an invalid regular expression.  
+  [Kyle Fuller](https://github.com/kylef)
+
+
 ## 0.29.0
 [CocoaPods](https://github.com/CocoaPods/CocoaPods/compare/0.28.0...0.29.0)
 • [CocoaPods-core](https://github.com/CocoaPods/Core/compare/0.28.0...0.29.0)

lib/cocoapods/command/search.rb

@@ -35,6 +35,10 @@ module Pod
       def validate!
         super
         help! "A search query is required." unless @query
+
+        /#{@query.join(' ').strip}/
+      rescue RegexpError
+        help! "A valid regular expression is required."
       end
 
       def run

spec/functional/command/search_spec.rb

@@ -49,7 +49,11 @@ module Pod
       output = run_command('search', 'BananaLib', '--silent')
       output.should.include? 'BananaLib'
     end
-    
+
+    it "shows a friendly message when searching with invalid regex" do
+      lambda { run_command('search', '+') }.should.raise CLAide::Help
+    end
+
     describe "option --web" do
 
       extend SpecHelper::TemporaryRepos