git p4: add submit --dry-run option

A new option, "git p4 submit --dry-run" can be used to verify
what commits and labels would be moved into p4.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Acked-by: Luke Diamand <luke@diamand.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-p4.txt

@@ -269,6 +269,10 @@ These options can be used to modify 'git p4 submit' behavior.
 	Export tags from git as p4 labels. Tags found in git are applied
 	to the perforce working directory.
 
+--dry-run, -n::
+	Show just what commits would be submitted to p4; do not change
+	state in git or p4.
+
 Rebase options
 ~~~~~~~~~~~~~~
 These options can be used to modify 'git p4 rebase' behavior.

git-p4.py

@@ -853,12 +853,14 @@ class P4Submit(Command, P4UserMap):
                 # preserve the user, requires relevant p4 permissions
                 optparse.make_option("--preserve-user", dest="preserveUser", action="store_true"),
                 optparse.make_option("--export-labels", dest="exportLabels", action="store_true"),
+                optparse.make_option("--dry-run", "-n", dest="dry_run", action="store_true"),
         ]
         self.description = "Submit changes from git to the perforce depot."
         self.usage += " [name of git branch to submit into perforce depot]"
         self.origin = ""
         self.detectRenames = False
         self.preserveUser = gitConfig("git-p4.preserveUser").lower() == "true"
+        self.dry_run = False
         self.isWindows = (platform.system() == "Windows")
         self.exportLabels = False
         self.p4HasMoveCommand = p4_has_command("move")
@@ -1366,6 +1368,9 @@ class P4Submit(Command, P4UserMap):
             for mapping in clientSpec.mappings:
                 labelTemplate += "\t%s\n" % mapping.depot_side.path
 
+            if self.dry_run:
+                print "Would create p4 label %s for tag" % name
+            else:
                 p4_write_pipe(["label", "-i"], labelTemplate)
 
                 # Use the label
@@ -1432,6 +1437,9 @@ class P4Submit(Command, P4UserMap):
             os.makedirs(self.clientPath)
 
         chdir(self.clientPath)
+        if self.dry_run:
+            print "Would synchronize p4 checkout in %s" % self.clientPath
+        else:
             print "Synchronizing p4 checkout..."
             if new_client_dir:
                 # old one was destroyed, and maybe nobody told p4
@@ -1488,9 +1496,16 @@ class P4Submit(Command, P4UserMap):
         # Apply the commits, one at a time.  On failure, ask if should
         # continue to try the rest of the patches, or quit.
         #
+        if self.dry_run:
+            print "Would apply"
         applied = []
         last = len(commits) - 1
         for i, commit in enumerate(commits):
+            if self.dry_run:
+                print " ", read_pipe(["git", "show", "-s",
+                                      "--format=format:%h %s", commit])
+                ok = True
+            else:
                 ok = self.applyCommit(commit)
             if ok:
                 applied.append(commit)
@@ -1515,7 +1530,9 @@ class P4Submit(Command, P4UserMap):
 
         chdir(self.oldWorkingDirectory)
 
-        if len(commits) == len(applied):
+        if self.dry_run:
+            pass
+        elif len(commits) == len(applied):
             print "All commits applied!"
 
             sync = P4Sync()

t/t9807-git-p4-submit.sh

@@ -54,6 +54,47 @@ test_expect_success 'submit --origin' '
 	)
 '
 
+test_expect_success 'submit --dry-run' '
+	test_when_finished cleanup_git &&
+	git p4 clone --dest="$git" //depot &&
+	(
+		cd "$git" &&
+		test_commit "dry-run1" &&
+		test_commit "dry-run2" &&
+		git p4 submit --dry-run >out &&
+		test_i18ngrep "Would apply" out
+	) &&
+	(
+		cd "$cli" &&
+		test_path_is_missing "dry-run1.t" &&
+		test_path_is_missing "dry-run2.t"
+	)
+'
+
+test_expect_success 'submit --dry-run --export-labels' '
+	test_when_finished cleanup_git &&
+	git p4 clone --dest="$git" //depot &&
+	(
+		cd "$git" &&
+		echo dry-run1 >dry-run1 &&
+		git add dry-run1 &&
+		git commit -m "dry-run1" dry-run1 &&
+		git config git-p4.skipSubmitEdit true &&
+		git p4 submit &&
+		echo dry-run2 >dry-run2 &&
+		git add dry-run2 &&
+		git commit -m "dry-run2" dry-run2 &&
+		git tag -m "dry-run-tag1" dry-run-tag1 HEAD^ &&
+		git p4 submit --dry-run --export-labels >out &&
+		test_i18ngrep "Would create p4 label" out
+	) &&
+	(
+		cd "$cli" &&
+		test_path_is_file "dry-run1" &&
+		test_path_is_missing "dry-run2"
+	)
+'
+
 test_expect_success 'submit with allowSubmit' '
 	test_when_finished cleanup_git &&
 	git p4 clone --dest="$git" //depot &&