git-codereview: add sync-branch -merge-back-to-parentv1.0.0

Dev branches come to an end.
Making sync-branch help that process instead of forcing
people to follow a playbook will help avoid mistakes.
The flag name was chosen to be very unlikely to be used
accidentally, and the commit subject and message both
are distinct to make clear to reviewers what they are being
asked to +2.

The Merge List is also included in full and is likely to be
quite large, yet another signal for everyone involved about
the magnitude and weight of the change.

Change-Id: I91cdda2b85cd3811711a339f4f3290fee109022e

1 files changed, 91 insertions, 4 deletions

diff --git a/git-codereview/sync_test.go b/git-codereview/sync_test.go
index d8733c8..0d3978d 100644
--- a/git-codereview/sync_test.go
+++ b/git-codereview/sync_test.go
@@ -5,6 +5,9 @@
 package main
 
 import (
+	"bytes"
+	"io/ioutil"
+	"path/filepath"
 	"strings"
 	"testing"
 )
@@ -79,7 +82,7 @@ func TestSyncRebase(t *testing.T) {
 	// submit first two CLs - gt.serverWork does same thing gt.work does, but on server
 
 	gt.serverWork(t)
-	gt.serverWorkUnrelated(t) // wedge in unrelated work to get different hashes
+	gt.serverWorkUnrelated(t, "") // wedge in unrelated work to get different hashes
 	gt.serverWork(t)
 
 	testMain(t, "sync")
@@ -215,9 +218,9 @@ func TestSyncBranch(t *testing.T) {
 	gt.serverWork(t)
 	gt.serverWork(t)
 	trun(t, gt.server, "git", "checkout", "dev.branch")
-	gt.serverWorkUnrelated(t)
-	gt.serverWorkUnrelated(t)
-	gt.serverWorkUnrelated(t)
+	gt.serverWorkUnrelated(t, "")
+	gt.serverWorkUnrelated(t, "")
+	gt.serverWorkUnrelated(t, "")
 	trun(t, gt.server, "git", "checkout", "main")
 
 	testMain(t, "change", "dev.branch")
@@ -232,6 +235,90 @@ func TestSyncBranch(t *testing.T) {
 		"Run 'git codereview mail' to send for review.")
 }
 
+func TestSyncBranchMergeBack(t *testing.T) {
+	gt := newGitTest(t)
+	defer gt.done()
+
+	// server does not default to having a codereview.cfg on main,
+	// but sync-branch requires one.
+	var mainCfg = []byte("branch: main\n")
+	ioutil.WriteFile(filepath.Join(gt.server, "codereview.cfg"), mainCfg, 0666)
+	trun(t, gt.server, "git", "add", "codereview.cfg")
+	trun(t, gt.server, "git", "commit", "-m", "config for main", "codereview.cfg")
+
+	gt.serverWork(t)
+	gt.serverWork(t)
+	trun(t, gt.server, "git", "checkout", "dev.branch")
+	gt.serverWorkUnrelated(t, "work on dev.branch#1")
+	gt.serverWorkUnrelated(t, "work on dev.branch#2")
+	gt.serverWorkUnrelated(t, "work on dev.branch#3")
+	trun(t, gt.server, "git", "checkout", "main")
+	testMain(t, "change", "dev.branch")
+
+	// Merge back should fail because there are
+	// commits in the parent that have not been merged here yet.
+	testMainDied(t, "sync-branch", "--merge-back-to-parent")
+	testNoStdout(t)
+	testPrintedStderr(t, "parent has new commits")
+
+	// Bring them in, creating a merge commit.
+	testMain(t, "sync-branch")
+
+	// Merge back should still fail - merge commit not submitted yet.
+	testMainDied(t, "sync-branch", "--merge-back-to-parent")
+	testNoStdout(t)
+	testPrintedStderr(t, "pending changes exist")
+
+	// Push the changes back to the server.
+	// (In a real system this would happen through Gerrit.)
+	trun(t, gt.client, "git", "push", "origin")
+
+	devHash := trim(trun(t, gt.client, "git", "rev-parse", "HEAD"))
+
+	// Nothing should be pending.
+	testMain(t, "pending", "-c")
+	testPrintedStdout(t, "!+")
+
+	// This time should work.
+	testMain(t, "sync-branch", "--merge-back-to-parent")
+	testPrintedStdout(t,
+		"\n\tall: REVERSE MERGE dev.branch ("+devHash[:7]+") into main",
+		"This commit is a REVERSE MERGE.",
+		"It merges dev.branch back into its parent branch, main.",
+		"This marks the end of development on dev.branch.",
+		"Merge List:",
+		"msg #2",
+		"!config for main",
+	)
+	testPrintedStderr(t, "Merge commit created.")
+
+	data, err := ioutil.ReadFile(filepath.Join(gt.client, "codereview.cfg"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(data, mainCfg) {
+		t.Fatalf("codereview.cfg not restored:\n%s", data)
+	}
+
+	// Check pending knows what branch it is on.
+	testMain(t, "pending", "-c")
+	testHideRevHashes(t)
+	testPrintedStdout(t,
+		"dev.branch REVHASH..REVHASH (current branch)", // no "tracking dev.branch" anymore
+		"REVHASH (merge=REVHASH)",
+		"Merge List:",
+		"!config for main",
+	)
+
+	// Check that mail sends the merge to the right place!
+	testMain(t, "mail", "-n")
+	testNoStdout(t)
+	testPrintedStderr(t,
+		"git push -q origin HEAD:refs/for/main",
+		"git tag -f dev.branch.mailed",
+	)
+}
+
 func TestSyncBranchConflict(t *testing.T) {
 	gt := newGitTest(t)
 	defer gt.done()