Milo: Increase test coverage for appengine/buildbot

milo/appengine/buildbot/buildinfo.go

 // Copyright 2017 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package buildbot
 
 import (
         "fmt"
         "strconv"
         "strings"
@@ skipping 44 matching lines @@
 //      3) Fetches the LogDog annotation stream and resolves it into a Step.
 //      4) Merges some operational BuildBot build information into the Step.
 func (p *BuildInfoProvider) GetBuildInfo(c context.Context, req *milo.BuildInfoRequest_BuildBot,
         projectHint cfgtypes.ProjectName) (*milo.BuildInfoResponse, error) {
 
         logging.Infof(c, "Loading build info for master %q, builder %q, build #%d",
                 req.MasterName, req.BuilderName, req.BuildNumber)
 
         // Load the BuildBot build from datastore.
         build, err := getBuild(c, req.MasterName, req.BuilderName, int(req.BuildNumber))
-        if err != nil {
-                if err == errBuildNotFound {
-                        return nil, grpcutil.Errf(codes.NotFound, "Build #%d for master %q, builder %q was not found",
-                                req.BuildNumber, req.MasterName, req.BuilderName)
-                }
-
+        switch err {
+        case errBuildNotFound:
+                return nil, grpcutil.Errf(codes.NotFound, "Build #%d for master %q, builder %q was not found",
+                        req.BuildNumber, req.MasterName, req.BuilderName)
+        case errNotAuth:
+                return nil, grpcutil.Unauthenticated
+        case nil:
+                // continue
+        default:
                 logging.WithError(err).Errorf(c, "Failed to load build info.")
                 return nil, grpcutil.Internal
         }
 
         // Create a new LogDog client.
         client, err := p.newLogdogClient(c)
         if err != nil {
                 logging.WithError(err).Errorf(c, "Failed to create LogDog client.")
                 return nil, grpcutil.Internal
         }
@@ skipping 180 matching lines @@
                 allProps.Add(prop.Name)
 
                 step.Property = append(step.Property, &miloProto.Step_Property{
                         Name:  prop.Name,
                         Value: fmt.Sprintf("%v", prop.Value),
                 })
         }
 
         return nil
 }