[milo] {buildbucket,buildbot,swarming,logdog} -> backends/*.

milo/appengine/job_source/buildbot/build.go

Index: milo/appengine/job_source/buildbot/build.go
diff --git a/milo/appengine/buildbot/build.go b/milo/appengine/job_source/buildbot/build.go
similarity index 97%
rename from milo/appengine/buildbot/build.go
rename to milo/appengine/job_source/buildbot/build.go
index 1d88681de1e3d1e6f65cb10094e320d21c25313f..52bc2e64b8ade8d3db254a86b398b9f284461a20 100644
--- a/milo/appengine/buildbot/build.go
+++ b/milo/appengine/job_source/buildbot/build.go
@@ -447,44 +447,45 @@ func sourcestamp(c context.Context, b *buildbotBuild) *resp.SourceStamp {
 	return ss
 }
 
-func getDebugBuild(c context.Context, builder string, buildNum int) (*buildbotBuild, error) {
+func renderBuild(c context.Context, b *buildbotBuild) *resp.MiloBuild {
+	// Modify the build for rendering.
+	updatePostProcessBuild(b)
+
+	// TODO(hinoka): Do all fields concurrently.
+	return &resp.MiloBuild{
+		SourceStamp:   sourcestamp(c, b),
+		Summary:       summary(c, b),
+		Components:    components(b),
+		PropertyGroup: properties(b),
+		Blame:         blame(b),
+	}
+}
+
+// DebugBuild fetches a debugging build for testing.
+func DebugBuild(c context.Context, relBuildbotDir string, builder string, buildNum int) (*resp.MiloBuild, error) {
 	fname := fmt.Sprintf("%s.%d.json", builder, buildNum)
 	// ../buildbot below assumes that
 	// - this code is not executed by tests outside of this dir
 	// - this dir is a sibling of frontend dir
-	path := filepath.Join("..", "buildbot", "testdata", fname)
+	path := filepath.Join(relBuildbotDir, "testdata", fname)
 	raw, err := ioutil.ReadFile(path)
 	if err != nil {
 		return nil, err
 	}
 	b := &buildbotBuild{}
-	return b, json.Unmarshal(raw, b)
+	if err := json.Unmarshal(raw, b); err != nil {
+		return nil, err
+	}
+	return renderBuild(c, b), nil
 }
 
-// build fetches a buildbot build and translates it into a miloBuild.
+// Build fetches a buildbot build and translates it into a miloBuild.
 func Build(c context.Context, master, builder string, buildNum int) (*resp.MiloBuild, error) {
-	var b *buildbotBuild
-	var err error
-	if master == "debug" {
-		b, err = getDebugBuild(c, builder, buildNum)
-	} else {
-		b, err = getBuild(c, master, builder, buildNum)
-	}
+	b, err := getBuild(c, master, builder, buildNum)
 	if err != nil {
 		return nil, err
 	}
-
-	// Modify the build for rendering.
-	updatePostProcessBuild(b)
-
-	// TODO(hinoka): Do all fields concurrently.
-	return &resp.MiloBuild{
-		SourceStamp:   sourcestamp(c, b),
-		Summary:       summary(c, b),
-		Components:    components(b),
-		PropertyGroup: properties(b),
-		Blame:         blame(b),
-	}, nil
+	return renderBuild(c, b), nil
 }
 
 // updatePostProcessBuild transforms a build from its raw JSON format into the