git-svn: New flag to emulate empty directories

Adds a --preserve-empty-dirs flag to the clone operation that will detect
empty directories in the remote Subversion repository and create placeholder
files in the corresponding local Git directories.  This allows "empty"
directories to exist in the history of a Git repository.

Also adds the --placeholder-file flag to control the name of any placeholder
files created.  Default value is ".gitignore".

Signed-off-by: Ray Chen <rchen@cs.umd.edu>
Acked-by: Eric Wong <normalperson@yhbt.net>

1 files changed, 153 insertions, 0 deletions

diff --git a/t/t9160-git-svn-preserve-empty-dirs.sh b/t/t9160-git-svn-preserve-empty-dirs.sh
new file mode 100755
index 0000000..b4a4434
--- /dev/null
+++ b/t/t9160-git-svn-preserve-empty-dirs.sh
@@ -0,0 +1,153 @@
+#!/bin/sh
+#
+# Copyright (c) 2011 Ray Chen
+#
+
+test_description='git svn test (option --preserve-empty-dirs)
+
+This test uses git to clone a Subversion repository that contains empty
+directories, and checks that corresponding directories are created in the
+local Git repository with placeholder files.'
+
+. ./lib-git-svn.sh
+
+say 'define NO_SVN_TESTS to skip git svn tests'
+GIT_REPO=git-svn-repo
+
+test_expect_success 'initialize source svn repo containing empty dirs' '
+	svn_cmd mkdir -m x "$svnrepo"/trunk &&
+	svn_cmd co "$svnrepo"/trunk "$SVN_TREE" &&
+	(
+		cd "$SVN_TREE" &&
+		mkdir -p 1 2 3/a 3/b 4 5 6 &&
+		echo "First non-empty file"  > 2/file1.txt &&
+		echo "Second non-empty file" > 2/file2.txt &&
+		echo "Third non-empty file"  > 3/a/file1.txt &&
+		echo "Fourth non-empty file" > 3/b/file1.txt &&
+		svn_cmd add 1 2 3 4 5 6 &&
+		svn_cmd commit -m "initial commit" &&
+
+		mkdir 4/a &&
+		svn_cmd add 4/a &&
+		svn_cmd commit -m "nested empty directory" &&
+		mkdir 4/a/b &&
+		svn_cmd add 4/a/b &&
+		svn_cmd commit -m "deeply nested empty directory" &&
+		mkdir 4/a/b/c &&
+		svn_cmd add 4/a/b/c &&
+		svn_cmd commit -m "really deeply nested empty directory" &&
+		echo "Kill the placeholder file" > 4/a/b/c/foo &&
+		svn_cmd add 4/a/b/c/foo &&
+		svn_cmd commit -m "Regular file to remove placeholder" &&
+
+		svn_cmd del 2/file2.txt &&
+		svn_cmd del 3/b &&
+		svn_cmd commit -m "delete non-last entry in directory" &&
+
+		svn_cmd del 2/file1.txt &&
+		svn_cmd del 3/a &&
+		svn_cmd commit -m "delete last entry in directory" &&
+
+		echo "Conflict file" > 5/.placeholder &&
+		mkdir 6/.placeholder &&
+		svn_cmd add 5/.placeholder 6/.placeholder &&
+		svn_cmd commit -m "Placeholder Namespace conflict"
+	) &&
+	rm -rf "$SVN_TREE"
+'
+
+test_expect_success 'clone svn repo with --preserve-empty-dirs' '
+	git svn clone "$svnrepo"/trunk --preserve-empty-dirs "$GIT_REPO"
+'
+
+# "$GIT_REPO"/1 should only contain the placeholder file.
+test_expect_success 'directory empty from inception' '
+	test -f "$GIT_REPO"/1/.gitignore &&
+	test $(find "$GIT_REPO"/1 -type f | wc -l) = "1"
+'
+
+# "$GIT_REPO"/2 and "$GIT_REPO"/3 should only contain the placeholder file.
+test_expect_success 'directory empty from subsequent svn commit' '
+	test -f "$GIT_REPO"/2/.gitignore &&
+	test $(find "$GIT_REPO"/2 -type f | wc -l) = "1" &&
+	test -f "$GIT_REPO"/3/.gitignore &&
+	test $(find "$GIT_REPO"/3 -type f | wc -l) = "1"
+'
+
+# No placeholder files should exist in "$GIT_REPO"/4, even though one was
+# generated for every sub-directory at some point in the repo's history.
+test_expect_success 'add entry to previously empty directory' '
+	test $(find "$GIT_REPO"/4 -type f | wc -l) = "1" &&
+	test -f "$GIT_REPO"/4/a/b/c/foo
+'
+
+# The HEAD~2 commit should not have introduced .gitignore placeholder files.
+test_expect_success 'remove non-last entry from directory' '
+	(
+		cd "$GIT_REPO" &&
+		git checkout HEAD~2
+	) &&
+	test_must_fail test -f "$GIT_REPO"/2/.gitignore &&
+	test_must_fail test -f "$GIT_REPO"/3/.gitignore
+'
+
+# After re-cloning the repository with --placeholder-file specified, there
+# should be 5 files named ".placeholder" in the local Git repo.
+test_expect_success 'clone svn repo with --placeholder-file specified' '
+	rm -rf "$GIT_REPO" &&
+	git svn clone "$svnrepo"/trunk --preserve-empty-dirs \
+		--placeholder-file=.placeholder "$GIT_REPO" &&
+	find "$GIT_REPO" -type f -name ".placeholder" &&
+	test $(find "$GIT_REPO" -type f -name ".placeholder" | wc -l) = "5"
+'
+
+# "$GIT_REPO"/5/.placeholder should be a file, and non-empty.
+test_expect_success 'placeholder namespace conflict with file' '
+	test -s "$GIT_REPO"/5/.placeholder
+'
+
+# "$GIT_REPO"/6/.placeholder should be a directory, and the "$GIT_REPO"/6 tree
+# should only contain one file: the placeholder.
+test_expect_success 'placeholder namespace conflict with directory' '
+	test -d "$GIT_REPO"/6/.placeholder &&
+	test -f "$GIT_REPO"/6/.placeholder/.placeholder &&
+	test $(find "$GIT_REPO"/6 -type f | wc -l) = "1"
+'
+
+# Prepare a second set of svn commits to test persistence during rebase.
+test_expect_success 'second set of svn commits and rebase' '
+	svn_cmd co "$svnrepo"/trunk "$SVN_TREE" &&
+	(
+		cd "$SVN_TREE" &&
+		mkdir -p 7 &&
+		echo "This should remove placeholder" > 1/file1.txt &&
+		echo "This should not remove placeholder" > 5/file1.txt &&
+		svn_cmd add 7 1/file1.txt 5/file1.txt &&
+		svn_cmd commit -m "subsequent svn commit for persistence tests"
+	) &&
+	rm -rf "$SVN_TREE" &&
+	(
+		cd "$GIT_REPO" &&
+		git svn rebase
+	)
+'
+
+# Check that --preserve-empty-dirs and --placeholder-file flag state
+# stays persistent over multiple invocations.
+test_expect_success 'flag persistence during subsqeuent rebase' '
+	test -f "$GIT_REPO"/7/.placeholder &&
+	test $(find "$GIT_REPO"/7 -type f | wc -l) = "1"
+'
+
+# Check that placeholder files are properly removed when unnecessary,
+# even across multiple invocations.
+test_expect_success 'placeholder list persistence during subsqeuent rebase' '
+	test -f "$GIT_REPO"/1/file1.txt &&
+	test $(find "$GIT_REPO"/1 -type f | wc -l) = "1" &&
+
+	test -f "$GIT_REPO"/5/file1.txt &&
+	test -f "$GIT_REPO"/5/.placeholder &&
+	test $(find "$GIT_REPO"/5 -type f | wc -l) = "2"
+'
+
+test_done