test-lib.sh: introduce test_commit() and test_merge() helpers

Often we just need to add a commit with a given (short) name, that will
be tagged with the same name.  Now, relatively complicated graphs can be
constructed easily and in a clear fashion:

	test_commit A &&
	test_commit B &&
	git checkout A &&
	test_commit C &&
	test_merge D B

will construct this graph:

	A - B
	  \   \
	    C - D

For simplicity, files whose name is the lower case version of the commit
message (to avoid a warning about ambiguous names) will be committed, with
the corresponding commit messages as contents.

If you need to provide a different file/different contents, you can use
the more explicit form

	test_commit $MESSAGE $FILENAME $CONTENTS

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 41d5a5996..c1839f70b 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -193,6 +193,31 @@ test_tick () {
 	export GIT_COMMITTER_DATE GIT_AUTHOR_DATE
 }
 
+# Call test_commit with the arguments "<message> [<file> [<contents>]]"
+#
+# This will commit a file with the given contents and the given commit
+# message.  It will also add a tag with <message> as name.
+#
+# Both <file> and <contents> default to <message>.
+
+test_commit () {
+	file=${2:-$(echo "$1" | tr 'A-Z' 'a-z')}
+	echo "${3-$1}" > "$file" &&
+	git add "$file" &&
+	test_tick &&
+	git commit -m "$1" &&
+	git tag "$1"
+}
+
+# Call test_merge with the arguments "<message> <commit>", where <commit>
+# can be a tag pointing to the commit-to-merge.
+
+test_merge () {
+	test_tick &&
+	git merge -m "$1" "$2" &&
+	git tag "$1"
+}
+
 # You are not expected to call test_ok_ and test_failure_ directly, use
 # the text_expect_* functions instead.