[PATCH/RFC] Add test_repo_expect_success for running tests in a new repository

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

This could be convenient when tests are independent from the rest in the
same file. Normally we would do this

test_expect_success '...' '
	git init foo &&
	(
		cd foo &&
		<script>
	)
'

Now we can write a shorter version

test_repo_expect_success '...' '
	<script>
'

The other function, test_subdir_expect_success, expands the script to
"( cd <repo> && <script> )", which can be useful for grouping a series of
tests that operate on the same repository in a subdir, e.g.

test_expect_success 'create repo abc' 'test_create_repo abc'
test_subdir_expect_success abc '...' <script>
test_subdir_expect_success abc '...' <another-script>

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Lately I start to add more and more tests in this style. So this
 looks like a good change to me.

 t/README                | 15 +++++++++++++++
 t/test-lib-functions.sh | 20 ++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/t/README b/t/README
index 35438bc..ee761af 100644
--- a/t/README
+++ b/t/README
@@ -738,6 +738,21 @@ library for your script to use.
    the symbolic link in the file system and a part that does; then only
    the latter part need be protected by a SYMLINKS prerequisite (see below).
 
+ - test_subdir_expect_success <subdir> [<prereq>] <message> <script>
+   test_subdir_expect_success <subdir> <prereq> <message> <script> <prologue>
+
+   Expands to
+
+        test_expect_success [<prereq>] <message> "( cd <subdir> && <script> )"
+   or
+
+        test_expect_success <prereq> <message> "<prologue> && ( cd <subdir> && <script> )"
+
+ - test_repo_expect_success [<prereq>] <message> <script>
+
+   Create a new repository and perform <script> inside this repository
+   in a subshell.
+
 Prerequisites
 -------------
 
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index e8d3c0f..45d7423 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -394,6 +394,26 @@ test_expect_success () {
 	test_finish_
 }
 
+test_subdir_expect_success () {
+	local subdir="$1"
+	shift
+	case "$#" in
+		2) test_expect_success "$1" "( cd $subdir && $2 )";;
+		3) test_expect_success "$1" "$2" "( cd $subdir && $3 )";;
+		4) test_expect_success "$1" "$2" "$4 && ( cd $subdir && $3 )";;
+		*) error "bug in the test script: not 3-5 parameters to test-subdir-expect-success";;
+	esac
+}
+
+test_repo_expect_success () {
+	local repo=repo-$(($test_count+1))
+	case "$#" in
+		2) test_subdir_expect_success "$repo" '' "$1" "$2" "test_create_repo $repo";;
+		3) test_subdir_expect_success "$repo" "$1" "$2" "$3" "test_create_repo $repo";;
+		*) error "bug in the test script: not 2 or 3 parameters to test-repo-expect-success";;
+	esac
+}
+
 # test_external runs external test scripts that provide continuous
 # test output about their progress, and succeeds/fails on
 # zero/non-zero exit code.  It outputs the test output on stdout even
-- 
2.3.0.rc1.137.g477eb31