Write Cache to disk if an exception occurs while processing the Environment - fix #4

lib/rscons/environment.rb

@@ -176,6 +176,7 @@ module Rscons
       cache.clear_checksum_cache!
       targets_processed = {}
       unless @targets.empty?
+        begin
           process_target = proc do |target|
             targets_processed[target] ||= begin
               @targets[target][:sources].each do |src|
@@ -189,7 +190,6 @@ module Rscons
                                    cache,
                                    @targets[target][:vars] || {})
               unless result
-              cache.write
                 raise BuildError.new("Failed to build #{target}")
               end
               result
@@ -198,9 +198,11 @@ module Rscons
           @targets.each do |target, target_params|
             process_target.call(target)
           end
+        ensure
           cache.write
         end
       end
+    end
 
     # Clear all targets registered for the Environment.
     def clear_targets

spec/rscons/environment_spec.rb

@@ -176,6 +176,21 @@ module Rscons
 
         expect { env.process }.to raise_error BuildError, /Failed.to.build.main.o/
       end
+
+      it "writes the cache when the Builder raises an exception" do
+        env = Environment.new
+        env.Object("module.o", "module.c")
+
+        cache = "cache"
+        Cache.should_receive(:instance).and_return(cache)
+        cache.should_receive(:clear_checksum_cache!)
+        env.stub(:run_builder) do |builder, target, sources, cache, vars|
+          raise "Ruby exception thrown by builder"
+        end
+        cache.should_receive(:write)
+
+        expect { env.process }.to raise_error RuntimeError, /Ruby exception thrown by builder/
+      end
     end
 
     describe "#clear_targets" do