omaha: Make the trivial server to only return newer packages.

This is for adding related test in TCO.

omaha/trivial_server.go

@@ -18,6 +18,8 @@ import (
 	"fmt"
 	"net/http"
 	"path"
+
+	"github.com/blang/semver"
 )
 
 const pkg_prefix = "/packages/"
@@ -32,7 +34,22 @@ func (tu *trivialUpdater) CheckUpdate(req *Request, app *AppRequest) (*Update, e
 	if len(tu.Manifest.Packages) == 0 {
 		return nil, NoUpdate
 	}
-	return &tu.Update, nil
+
+	v1, err := semver.Make(app.Version)
+	if err != nil {
+		return nil, err
+	}
+
+	v2, err := semver.Make(tu.Manifest.Version)
+	if err != nil {
+		return nil, err
+	}
+
+	if v1.LT(v2) {
+		return &tu.Update, nil
+	}
+
+	return nil, NoUpdate
 }
 
 // trivialHandler serves up a single file.
@@ -98,3 +115,8 @@ func (ts *TrivialServer) AddPackage(file, name string) error {
 	ts.Mux.Handle(pkg_prefix+name, &trivialHandler{file})
 	return nil
 }
+
+// SetVersion sets the manifest's version with the provided one.
+func (ts *TrivialServer) SetVersion(version string) {
+	ts.tu.Manifest.Version = version
+}

omaha/trivial_server_test.go

@@ -59,6 +59,7 @@ func TestTrivialServer(t *testing.T) {
 	if err := s.AddPackage(tmp.Name(), "update.gz"); err != nil {
 		t.Fatal(err)
 	}
+	s.SetVersion(testAppVer)
 	go s.Serve()
 
 	buf, err := mkUpdateReq()
@@ -82,6 +83,37 @@ func TestTrivialServer(t *testing.T) {
 		t.Fatalf("failed to parse body: %v", err)
 	}
 
+	// Should get zero update because the version is already the latest.
+	if len(resp.Apps) != 1 ||
+		resp.Apps[0].UpdateCheck == nil ||
+		resp.Apps[0].UpdateCheck.Status != NoUpdate {
+		t.Fatalf("unexpected response: %#v", resp)
+	}
+
+	// Should get an update now.
+	s.SetVersion("999.999.999")
+
+	buf, err = mkUpdateReq()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	endpoint = fmt.Sprintf("http://%s/v1/update/", s.Addr())
+	res, err = http.Post(endpoint, "text/xml", buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer res.Body.Close()
+	if res.StatusCode != 200 {
+		t.Fatalf("failed to post: %v", res.Status)
+	}
+
+	dec = xml.NewDecoder(res.Body)
+	resp = &Response{}
+	if err := dec.Decode(resp); err != nil {
+		t.Fatalf("failed to parse body: %v", err)
+	}
+
 	if len(resp.Apps) != 1 ||
 		resp.Apps[0].UpdateCheck == nil ||
 		resp.Apps[0].UpdateCheck.Status != UpdateOK ||