[pod repo push] Improve error when podspec is missing

Ref #3494

lib/cocoapods/command/repo/push.rb

@@ -190,9 +190,15 @@ module Pod
         # @return [Array<Pathname>] The path of the specifications to push.
         #
         def podspec_files
-          files = Pathname.glob(@podspec || '*.podspec')
-          raise Informative, "Couldn't find any .podspec file in current directory" if files.empty?
-          files
+          if @podspec
+            path = Pathname(@podspec)
+            raise Informative, "Couldn't find #{@podspec}" unless path.exist?
+            [path]
+          else
+            files = Pathname.glob('*.podspec')
+            raise Informative, "Couldn't find any .podspec files in current directory" if files.empty?
+            files
+          end
         end
 
         # @return [Integer] The number of the podspec files to push.

spec/functional/command/repo/push_spec.rb

@@ -25,6 +25,12 @@ module Pod
       e.message.should.match(/Couldn't find any .podspec/)
     end
 
+    it "complains if it can't find the given podspec" do
+      repo_make('test_repo')
+      e = lambda { run_command('repo', 'push', 'test_repo', 'testspec.podspec') }.should.raise Pod::Informative
+      e.message.should.match(/Couldn't find testspec\.podspec/)
+    end
+
     it "it raises if the specification doesn't validate" do
       repo_make('test_repo')
       Dir.chdir(temporary_directory) do