[PATCH v7] git-prompt: make colourization consistent

[Joakim Petersen <joak-pet@online.no>]

The short upstream state indicator inherits the colour of the last short
state indicator before it (if there is one), and the sparsity state
indicator inherits this colour as well. This behaviour was introduced by
0ec7c23cdc6 (git-prompt: make upstream state indicator location
consistent, 2022-02-27), while before this change the aforementioned
indicators were white/the default text colour. Some examples to
illustrate this behaviour (assuming all indicators are enabled and
colourization is on):
 * If there is something in the stash, both the '$' and the short
   upstream state indicator following it will be blue.
 * If the local tree has new, untracked files and there is nothing in
   the stash, both the '%' and the short upstream state indicator
   will be red.
 * If all local changes are added to the index and the stash is empty,
   both the '+' and the short upstream state indicator following it will
   be green.
 * If the local tree is clean and there is nothing in the stash, the
   short upstream state indicator will be white/${default text colour}.

This appears to be an unintended side-effect of the change, and makes
little sense semantically (e.g. why is it bad to be in sync with
upstream when you have uncommitted local changes?). The cause of the
change in colourization is that previously, the short upstream state
indicator appeared immediately after the rebase/revert/bisect/merge
state indicator (note the position of $p in $gitstring):

	local f="$h$w$i$s$u"
	local gitstring="$c$b${f:+$z$f}${sparse}$r$p"
	
Said indicator is prepended with the clear colour code, and the short
upstream state indicator is thus also uncoloured. Now, the short
upstream state indicator follows the sequence of colourized indicators,
without any clearing of colour (again note the position of $p, now in
$f):

	local f="$h$w$i$s$u$p"
	local gitstring="$c$b${f:+$z$f}${sparse}$r${upstream}"

If the user is in a sparse checkout, the sparsity state indicator
follows a similar pattern to the short upstream state indicator.
However, clearing colour of the colourized indicators changes how the
sparsity state indicator is colourized, as it currently inherits (and
before the change referenced also inherited) the colour of the last
short state indicator before it. Reading the commit message of the
change that introduced the sparsity state indicator, afda36dbf3b
(git-prompt: include sparsity state as well, 2020-06-21), it appears
this colourization also was unintended, so clearing the colour for said
indicator further increases consistency.

Make the colourization of these state indicators consistent by making
all colourized indicators clear their own colour. Make colouring of $c
dependent on it not being empty, as it is no longer being used to colour
the branch name. Move clearing of $b's prefix to before colourization so
it gets cleared properly when colour codes are inserted into it. These
changes make changing the layout of the prompt less prone to unintended
colour changes in the future.

Change coloured Bash prompt tests to reflect the colourization changes:
 * Move the colour codes to wrap the expected content of the expanded
   $__git_ps1_branch_name in all tests.
 * Insert a clear-colour code after the symbol for the first indicator
   in "prompt - bash color pc mode - dirty status indicator - dirty
   index and worktree", to reflect that all indicators should clear
   their own colour.

Signed-off-by: Joakim Petersen <joak-pet@online.no>
---
Changes since v6:
 * Remove repeated statements and move all explanation of what the patch
   does to the latter part of the message.
 * Add a short statement about other benefits of the behavioural change.

Range-diff against v6:
1:  50765eeb95 = 1:  e25738c667 git-prompt: make colourization consistent

 contrib/completion/git-prompt.sh | 22 ++++++++++++----------
 t/t9903-bash-prompt.sh           | 18 +++++++++---------
 2 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index 87b2b916c0..cb01c2fd5d 100644
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh
@@ -245,7 +245,8 @@ __git_ps1_show_upstream ()
 
 # Helper function that is meant to be called from __git_ps1.  It
 # injects color codes into the appropriate gitstring variables used
-# to build a gitstring.
+# to build a gitstring. Colored variables are responsible for clearing
+# their own color.
 __git_ps1_colorize_gitstring ()
 {
 	if [[ -n ${ZSH_VERSION-} ]]; then
@@ -271,22 +272,23 @@ __git_ps1_colorize_gitstring ()
 	else
 		branch_color="$bad_color"
 	fi
-	c="$branch_color$c"
+	if [ -n "$c" ]; then
+		c="$branch_color$c$c_clear"
+	fi
+	b="$branch_color$b$c_clear"
 
-	z="$c_clear$z"
-	if [ "$w" = "*" ]; then
-		w="$bad_color$w"
+	if [ -n "$w" ]; then
+		w="$bad_color$w$c_clear"
 	fi
 	if [ -n "$i" ]; then
-		i="$ok_color$i"
+		i="$ok_color$i$c_clear"
 	fi
 	if [ -n "$s" ]; then
-		s="$flags_color$s"
+		s="$flags_color$s$c_clear"
 	fi
 	if [ -n "$u" ]; then
-		u="$bad_color$u"
+		u="$bad_color$u$c_clear"
 	fi
-	r="$c_clear$r"
 }
 
 # Helper function to read the first line of a file into a variable.
@@ -554,6 +556,7 @@ __git_ps1 ()
 		fi
 	fi
 
+	b=${b##refs/heads/}
 	local z="${GIT_PS1_STATESEPARATOR-" "}"
 
 	# NO color option unless in PROMPT_COMMAND mode or it's Zsh
@@ -563,7 +566,6 @@ __git_ps1 ()
 		fi
 	fi
 
-	b=${b##refs/heads/}
 	if [ $pcmode = yes ] && [ $ps1_expanded = yes ]; then
 		__git_ps1_branch_name=$b
 		b="\${__git_ps1_branch_name}"
diff --git a/t/t9903-bash-prompt.sh b/t/t9903-bash-prompt.sh
index bbd513bab0..abd82eec35 100755
--- a/t/t9903-bash-prompt.sh
+++ b/t/t9903-bash-prompt.sh
@@ -541,7 +541,7 @@ test_expect_success 'prompt - pc mode' '
 '
 
 test_expect_success 'prompt - bash color pc mode - branch name' '
-	printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear}):AFTER\\nmain" >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name}):AFTER\\n${c_green}main${c_clear}" >expected &&
 	(
 		GIT_PS1_SHOWCOLORHINTS=y &&
 		__git_ps1 "BEFORE:" ":AFTER" >"$actual" &&
@@ -551,7 +551,7 @@ test_expect_success 'prompt - bash color pc mode - branch name' '
 '
 
 test_expect_success 'prompt - bash color pc mode - detached head' '
-	printf "BEFORE: (${c_red}\${__git_ps1_branch_name}${c_clear}):AFTER\\n(%s...)" $(git log -1 --format="%h" b1^) >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name}):AFTER\\n${c_red}(%s...)"${c_clear} $(git log -1 --format="%h" b1^) >expected &&
 	git checkout b1^ &&
 	test_when_finished "git checkout main" &&
 	(
@@ -563,7 +563,7 @@ test_expect_success 'prompt - bash color pc mode - detached head' '
 '
 
 test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirty worktree' '
-	printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_red}*${c_clear}):AFTER\\nmain" >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name} ${c_red}*${c_clear}):AFTER\\n${c_green}main${c_clear}" >expected &&
 	echo "dirty" >file &&
 	test_when_finished "git reset --hard" &&
 	(
@@ -576,7 +576,7 @@ test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirt
 '
 
 test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirty index' '
-	printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_green}+${c_clear}):AFTER\\nmain" >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name} ${c_green}+${c_clear}):AFTER\\n${c_green}main${c_clear}" >expected &&
 	echo "dirty" >file &&
 	test_when_finished "git reset --hard" &&
 	git add -u &&
@@ -590,7 +590,7 @@ test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirt
 '
 
 test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirty index and worktree' '
-	printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_red}*${c_green}+${c_clear}):AFTER\\nmain" >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name} ${c_red}*${c_clear}${c_green}+${c_clear}):AFTER\\n${c_green}main${c_clear}" >expected &&
 	echo "dirty index" >file &&
 	test_when_finished "git reset --hard" &&
 	git add -u &&
@@ -605,7 +605,7 @@ test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirt
 '
 
 test_expect_success 'prompt - bash color pc mode - dirty status indicator - before root commit' '
-	printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_green}#${c_clear}):AFTER\\nmain" >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name} ${c_green}#${c_clear}):AFTER\\n${c_green}main${c_clear}" >expected &&
 	(
 		GIT_PS1_SHOWDIRTYSTATE=y &&
 		GIT_PS1_SHOWCOLORHINTS=y &&
@@ -617,7 +617,7 @@ test_expect_success 'prompt - bash color pc mode - dirty status indicator - befo
 '
 
 test_expect_success 'prompt - bash color pc mode - inside .git directory' '
-	printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear}):AFTER\\nGIT_DIR!" >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name}):AFTER\\n${c_green}GIT_DIR!${c_clear}" >expected &&
 	echo "dirty" >file &&
 	test_when_finished "git reset --hard" &&
 	(
@@ -631,7 +631,7 @@ test_expect_success 'prompt - bash color pc mode - inside .git directory' '
 '
 
 test_expect_success 'prompt - bash color pc mode - stash status indicator' '
-	printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_lblue}\$${c_clear}):AFTER\\nmain" >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name} ${c_lblue}\$${c_clear}):AFTER\\n${c_green}main${c_clear}" >expected &&
 	echo 2 >file &&
 	git stash &&
 	test_when_finished "git stash drop" &&
@@ -645,7 +645,7 @@ test_expect_success 'prompt - bash color pc mode - stash status indicator' '
 '
 
 test_expect_success 'prompt - bash color pc mode - untracked files status indicator' '
-	printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_red}%%${c_clear}):AFTER\\nmain" >expected &&
+	printf "BEFORE: (\${__git_ps1_branch_name} ${c_red}%%${c_clear}):AFTER\\n${c_green}main${c_clear}" >expected &&
 	(
 		GIT_PS1_SHOWUNTRACKEDFILES=y &&
 		GIT_PS1_SHOWCOLORHINTS=y &&
-- 
2.36.1