Fix regression from #6457 to ensure a correct error message is given when a spec is not found.

CHANGELOG.md

@@ -12,6 +12,10 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
 
 ##### Bug Fixes
 
+* Fix regression from #6457 to ensure a correct error message is given when a spec is not found.  
+  [Dimitris Koutsogiorgas](https://github.com/dnkoutso)
+  [#6457](https://github.com/CocoaPods/CocoaPods/issues/6457)
+
 * Provide a better error message if a podspec is found but cannot be parsed.  
   [Dimitris Koutsogiorgas](https://github.com/dnkoutso)
   [#6457](https://github.com/CocoaPods/CocoaPods/issues/6457)

lib/cocoapods/external_sources/abstract_external_source.rb

@@ -116,10 +116,12 @@ module Pod
           rescue Pod::DSLError => e
             raise Informative, "Failed to load '#{name}' podspec: #{e.message}"
           rescue => _
-            raise Informative, "Unable to find a specification for '#{name}'."
+            raise Informative, "Failed to download '#{name}'."
           end
           spec = download_result.spec
 
+          raise Informative, "Unable to find a specification for '#{name}'." unless spec
+
           store_podspec(sandbox, spec)
           sandbox.store_pre_downloaded_pod(name)
           sandbox.store_checkout_source(name, download_result.checkout_options)

spec/unit/external_sources/abstract_external_source_spec.rb

@@ -36,6 +36,12 @@ module Pod
         end
       end
 
+      it 'raises a generic error if pre download fails' do
+        Downloader.stubs(:download).raises(Pod::Downloader::DownloaderError.new('Some generic exception'))
+        exception = lambda { @subject.send(:pre_download, config.sandbox) }.should.raise Informative
+        exception.message.should.include "Failed to download 'Reachability'"
+      end
+
       it 'raises appropriate error if a DSLError when storing a podspec from string' do
         podspec = 'Pod::Spec.new do |s|; error; end'
         should.raise(Informative) { @subject.send(:store_podspec, config.sandbox, podspec) }.
@@ -51,10 +57,10 @@ module Pod
       end
 
       it 'raises a generic error if a podspec was not found' do
-        Downloader.stubs(:download).raises(Pod::Downloader::DownloaderError.new('Some generic exception'))
-        should.raise(Informative) do
-          @subject.send(:pre_download, config.sandbox).message.should == "Unable to find a specification for 'Reachability'."
-        end
+        download_result = stub(:spec => nil)
+        Downloader.stubs(:download).returns(download_result)
+        exception = lambda { @subject.send(:pre_download, config.sandbox) }.should.raise Informative
+        exception.message.should.include "Unable to find a specification for 'Reachability'."
       end
     end