fix #12 - allow overriding dependency file suffix with DEPFILESUFFIX construction variable

spec/rscons/builders/object_spec.rb

@@ -2,19 +2,31 @@ module Rscons
   module Builders
     describe Object do
       let(:env) {Environment.new}
+      let(:cache) {double(Cache)}
       subject {Object.new}
 
       it "supports overriding CCCMD construction variable" do
-        cache = "cache"
-        allow(cache).to receive(:up_to_date?) { false }
-        allow(cache).to receive(:mkdir_p) { }
-        allow(cache).to receive(:register_build) { }
-        allow(FileUtils).to receive(:rm_f) { }
-        allow(File).to receive(:exists?) { false }
+        expect(cache).to receive(:up_to_date?).and_return(false)
+        expect(cache).to receive(:mkdir_p)
+        expect(FileUtils).to receive(:rm_f)
         expect(env).to receive(:execute).with("CC mod.o", ["llc", "mod.c"]).and_return(true)
+        expect(File).to receive(:exists?).and_return(false)
+        expect(cache).to receive(:register_build)
+
         subject.run("mod.o", ["mod.c"], cache, env, "CCCMD" => ["llc", "${_SOURCES}"])
       end
 
+      it "supports overriding DEPFILESUFFIX construction variable" do
+        expect(cache).to receive(:up_to_date?).and_return(false)
+        expect(cache).to receive(:mkdir_p)
+        expect(FileUtils).to receive(:rm_f)
+        expect(env).to receive(:execute).with(anything, %w[gcc -c -o f.o -MMD -MF f.d in.c]).and_return(true)
+        expect(File).to receive(:exists?).with("f.d").and_return(false)
+        expect(cache).to receive(:register_build)
+
+        subject.run("f.o", ["in.c"], cache, env, "DEPFILESUFFIX" => ".d")
+      end
+
       it "raises an error when given a source file with an unknown suffix" do
         expect { subject.run("mod.o", ["mod.xyz"], :cache, env, {}) }.to raise_error /unknown input file type: "mod.xyz"/
       end