t7527: test status with untracked-cache and fsmonitor--daemon

Create 2x2 test matrix with the untracked-cache and fsmonitor--daemon
features and a series of edits and verify that status output is
identical.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7527-builtin-fsmonitor.sh

@@ -216,6 +216,8 @@ test_expect_success 'setup' '
 	.gitignore
 	expect*
 	actual*
+	flush*
+	trace*
 	EOF
 
 	git -c core.fsmonitor=false add . &&
@@ -502,4 +504,117 @@ test_expect_success 'cleanup worktrees' '
 	stop_daemon_delete_repo wt-base
 '
 
+# The next few tests perform arbitrary/contrived file operations and
+# confirm that status is correct.  That is, that the data (or lack of
+# data) from fsmonitor doesn't cause incorrect results.  And doesn't
+# cause incorrect results when the untracked-cache is enabled.
+
+test_lazy_prereq UNTRACKED_CACHE '
+	git update-index --test-untracked-cache
+'
+
+test_expect_success 'Matrix: setup for untracked-cache,fsmonitor matrix' '
+	test_unconfig core.fsmonitor &&
+	git update-index --no-fsmonitor &&
+	test_might_fail git fsmonitor--daemon stop
+'
+
+matrix_clean_up_repo () {
+	git reset --hard HEAD &&
+	git clean -fd
+}
+
+matrix_try () {
+	uc=$1 &&
+	fsm=$2 &&
+	fn=$3 &&
+
+	if test $uc = true && test $fsm = false
+	then
+		# The untracked-cache is buggy when FSMonitor is
+		# DISABLED, so skip the tests for this matrix
+		# combination.
+		#
+		# We've observed random, occasional test failures on
+		# Windows and MacOS when the UC is turned on and FSM
+		# is turned off.  These are rare, but they do happen
+		# indicating that it is probably a race condition within
+		# the untracked cache itself.
+		#
+		# It usually happens when a test does F/D trickery and
+		# then the NEXT test fails because of extra status
+		# output from stale UC data from the previous test.
+		#
+		# Since FSMonitor is not involved in the error, skip
+		# the tests for this matrix combination.
+		#
+		return 0
+	fi &&
+
+	test_expect_success "Matrix[uc:$uc][fsm:$fsm] $fn" '
+		matrix_clean_up_repo &&
+		$fn &&
+		if test $uc = false && test $fsm = false
+		then
+			git status --porcelain=v1 >.git/expect.$fn
+		else
+			git status --porcelain=v1 >.git/actual.$fn &&
+			test_cmp .git/expect.$fn .git/actual.$fn
+		fi
+	'
+}
+
+uc_values="false"
+test_have_prereq UNTRACKED_CACHE && uc_values="false true"
+for uc_val in $uc_values
+do
+	if test $uc_val = false
+	then
+		test_expect_success "Matrix[uc:$uc_val] disable untracked cache" '
+			git config core.untrackedcache false &&
+			git update-index --no-untracked-cache
+		'
+	else
+		test_expect_success "Matrix[uc:$uc_val] enable untracked cache" '
+			git config core.untrackedcache true &&
+			git update-index --untracked-cache
+		'
+	fi
+
+	fsm_values="false true"
+	for fsm_val in $fsm_values
+	do
+		if test $fsm_val = false
+		then
+			test_expect_success "Matrix[uc:$uc_val][fsm:$fsm_val] disable fsmonitor" '
+				test_unconfig core.fsmonitor &&
+				git update-index --no-fsmonitor &&
+				test_might_fail git fsmonitor--daemon stop
+			'
+		else
+			test_expect_success "Matrix[uc:$uc_val][fsm:$fsm_val] enable fsmonitor" '
+				git config core.fsmonitor true &&
+				git fsmonitor--daemon start &&
+				git update-index --fsmonitor
+			'
+		fi
+
+		matrix_try $uc_val $fsm_val edit_files
+		matrix_try $uc_val $fsm_val delete_files
+		matrix_try $uc_val $fsm_val create_files
+		matrix_try $uc_val $fsm_val rename_files
+		matrix_try $uc_val $fsm_val file_to_directory
+		matrix_try $uc_val $fsm_val directory_to_file
+
+		if test $fsm_val = true
+		then
+			test_expect_success "Matrix[uc:$uc_val][fsm:$fsm_val] disable fsmonitor at end" '
+				test_unconfig core.fsmonitor &&
+				git update-index --no-fsmonitor &&
+				test_might_fail git fsmonitor--daemon stop
+			'
+		fi
+	done
+done
+
 test_done