mr create: Use remote source branch for commit logs

As reported in issue 635, in some circumstances the 'mr create' command
does not show the correct information when calculating the number of
commits or generating the commit log.

This happens because the commit comparison is done using the local
source branch which may have different content than the remote source
branch.

Use the remote source branch to calculate the number of commits and the
commit log changelog.

Signed-off-by: Prarit Bhargava <[email protected]>

cmd/mr_create.go

@@ -285,17 +285,18 @@ func mrText(base, head, sourceRemote, targetRemote string, coverLetterFormat boo
 		err       error
 	)
 	remoteBase := fmt.Sprintf("%s/%s", targetRemote, base)
+	targetBase := fmt.Sprintf("%s/%s", sourceRemote, head)
 	commitMsg = ""
 
-	numCommits := git.NumberCommits(remoteBase, head)
+	numCommits := git.NumberCommits(remoteBase, targetBase)
 	if numCommits == 1 {
 		commitMsg, err = git.LastCommitMessage()
 		if err != nil {
 			return "", err
 		}
 	}
 	if numCommits == 0 {
-		return "", errors.New("Aborting: Resulting Merge Request would have had 0 commits.")
+		return "", fmt.Errorf("Aborting: The resulting Merge Request from %s to %s has 0 commits.", remoteBase, targetBase)
 	}
 
 	const tmpl = `{{if .InitMsg}}{{.InitMsg}}{{end}}
@@ -312,7 +313,7 @@ func mrText(base, head, sourceRemote, targetRemote string, coverLetterFormat boo
 
 	mrTmpl := lab.LoadGitLabTmpl(lab.TmplMR)
 
-	commitLogs, err := git.Log(remoteBase, head)
+	commitLogs, err := git.Log(remoteBase, targetBase)
 	if err != nil {
 		return "", err
 	}

cmd/mr_create_test.go

@@ -9,15 +9,15 @@ import (
 // MR Create is tested in cmd/mr_test.go
 
 func Test_mrText(t *testing.T) {
-	text, err := mrText("master", "mrtest", "lab-testing", "origin", false)
+	text, err := mrText("master", "mrtest", "origin", "origin", false)
 	if err != nil {
 		t.Log(text)
 		t.Fatal(err)
 	}
 	require.Contains(t, text, `
 
 I am the default merge request template for lab
-# Requesting a merge into origin:master from lab-testing:mrtest (12 commits)
+# Requesting a merge into origin:master from origin:mrtest (12 commits)
 #
 # Write a message for this merge request. The first block
 # of text is the title and the rest is the description.
@@ -29,15 +29,15 @@ I am the default merge request template for lab
 }
 
 func Test_mrText_CoverLetter(t *testing.T) {
-	coverLetter, err := mrText("master", "mrtest", "lab-testing", "origin", true)
+	coverLetter, err := mrText("master", "mrtest", "origin", "origin", true)
 	if err != nil {
 		t.Log(coverLetter)
 		t.Fatal(err)
 	}
 	require.Contains(t, coverLetter, `
 
 I am the default merge request template for lab
-# Requesting a merge into origin:master from lab-testing:mrtest (12 commits)
+# Requesting a merge into origin:master from origin:mrtest (12 commits)
 #
 # Write a message for this merge request. The first block
 # of text is the title and the rest is the description.

internal/git/git.go

@@ -368,8 +368,8 @@ func NumberCommits(sha1, sha2 string) int {
 	cmd.Stderr = nil
 	CmdOut, err := cmd.Output()
 	if err != nil {
-		fmt.Printf("There are no commits between %s and %s\n", sha1, sha2)
-		log.Fatal(err)
+		// silently fail and handle the return of 0 at caller
+		return 0
 	}
 	numLines := strings.Count(string(CmdOut), "\n")
 	return numLines