[PATCH v4 3/3] test-lib-functions: keep user's debugger config files and TERM in 'debug'

["Philippe Blain via GitGitGadget" <gitgitgadget@xxxxxxxxx>]

From: Philippe Blain <levraiphilippeblain@xxxxxxxxx>

The 'debug' function in test-lib-functions.sh is used to invoke a
debugger at a specific line in a test. It inherits the value of HOME and
TERM set by 'test-lib.sh': HOME="$TRASH_DIRECTORY" and TERM=dumb.

Changing the value of HOME means that any customization configured in a
developers' debugger configuration file (like $HOME/.gdbinit or
$HOME/.lldbinit) are not available in the debugger invoked by
'test_pause'.

Changing the value of TERM to 'dumb' means that colored output
is disabled in the debugger.

To make the debugging experience with 'debug' more pleasant, leverage
the variable USER_HOME, added in the previous commit, to copy a
developer's ~/.gdbinit and ~/.lldbinit to the test HOME. We do not set
HOME to USER_HOME as in 'test_pause' to avoid user configuration in
$USER_HOME/.gitconfig from interfering with the command being debugged.

Note that we use a while loop and a heredoc to protect against
$USER_HOME containing spaces.

Also, add a flag to launch the debugger with the original value of
TERM, and add the same warning as for 'test_pause'.

Helped-by: Carlo Marcelo Arenas Belón <carenas@xxxxxxxxx>
Signed-off-by: Philippe Blain <levraiphilippeblain@xxxxxxxxx>
---
 t/README                |  6 ++--
 t/test-lib-functions.sh | 66 ++++++++++++++++++++++++++++++++---------
 2 files changed, 56 insertions(+), 16 deletions(-)

diff --git a/t/README b/t/README
index cc8be6e67ad..e924bd81e2d 100644
--- a/t/README
+++ b/t/README
@@ -800,10 +800,12 @@ see test-lib-functions.sh for the full list and their options.
    argument.  This is primarily meant for use during the
    development of a new test script.
 
- - debug <git-command>
+ - debug [options] <git-command>
 
    Run a git command inside a debugger. This is primarily meant for
-   use when debugging a failing test script.
+   use when debugging a failing test script. With '-t', use your
+   original TERM instead of test-lib.sh's "dumb", so that your
+   debugger interface has colors.
 
  - test_done
 
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 5bed34e47e0..8cec0e986e1 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -190,25 +190,63 @@ test_pause () {
 # Wrap git with a debugger. Adding this to a command can make it easier
 # to understand what is going on in a failing test.
 #
+# Usage: debug [options] <git command>
+#   -d <debugger>
+#   --debugger=<debugger>
+#	Use <debugger> instead of GDB
+#   -t
+#	Use your original TERM instead of test-lib.sh's "dumb".
+#	This usually restores color output in the debugger.
+#	WARNING: the command being debugged might behave differently than when
+#	running the test.
+#
 # Examples:
 #     debug git checkout master
 #     debug --debugger=nemiver git $ARGS
 #     debug -d "valgrind --tool=memcheck --track-origins=yes" git $ARGS
 debug () {
-	case "$1" in
-	-d)
-		GIT_DEBUGGER="$2" &&
-		shift 2
-		;;
-	--debugger=*)
-		GIT_DEBUGGER="${1#*=}" &&
-		shift 1
-		;;
-	*)
-		GIT_DEBUGGER=1
-		;;
-	esac &&
-	GIT_DEBUGGER="${GIT_DEBUGGER}" "$@" <&6 >&5 2>&7
+	GIT_DEBUGGER=1 &&
+	DEBUG_TERM=$TERM &&
+	while test $# != 0
+	do
+		case "$1" in
+		-t)
+			DEBUG_TERM="$USER_TERM"
+			;;
+		-d)
+			GIT_DEBUGGER="$2" &&
+			shift
+			;;
+		--debugger=*)
+			GIT_DEBUGGER="${1#*=}"
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done &&
+
+	dotfiles="
+	.gdbinit
+	.lldbinit
+	"
+	while read -r dotfile
+	do
+		dotfile="$USER_HOME/$dotfile" &&
+		test -f "$dotfile" && cp "$dotfile" "$HOME" || :
+	done <<-EOF &&
+	$dotfiles
+	EOF
+
+	TERM="$DEBUG_TERM" GIT_DEBUGGER="${GIT_DEBUGGER}" "$@" <&6 >&5 2>&7 &&
+
+	while read -r dotfile
+	do
+		rm -f "$HOME/$dotfile"
+	done <<-EOF
+	$dotfiles
+	EOF
 }
 
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