t7800: use single quotes for test bodies

In eb84c8b (git-difftool--helper: honor `--trust-exit-code` with
`--dir-diff`, 2024-02-20) we have started to loop around some of the
tests in t7800 so that they are reexecuted with slightly different
arguments. As part of that refactoring the quoting of test bodies was
changed from single quotes (') to double quotes (") so that the value of
the loop variable is accessible to the body.

As the test body is later on passed to eval this change was not required
though. Let's revert it back to use single quotes as usual in our tests.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

t/t7800-difftool.sh

@@ -93,42 +93,42 @@ test_expect_success 'difftool forwards arguments to diff' '
 
 for opt in '' '--dir-diff'
 do
-	test_expect_success "difftool ${opt:-without options} ignores exit code" "
+	test_expect_success "difftool ${opt:-without options} ignores exit code" '
 		test_config difftool.error.cmd false &&
 		git difftool ${opt} -y -t error branch
-	"
+	'
 
-	test_expect_success "difftool ${opt:-without options} forwards exit code with --trust-exit-code" "
+	test_expect_success "difftool ${opt:-without options} forwards exit code with --trust-exit-code" '
 		test_config difftool.error.cmd false &&
 		test_must_fail git difftool ${opt} -y --trust-exit-code -t error branch
-	"
+	'
 
-	test_expect_success "difftool ${opt:-without options} forwards exit code with --trust-exit-code for built-ins" "
+	test_expect_success "difftool ${opt:-without options} forwards exit code with --trust-exit-code for built-ins" '
 		test_config difftool.vimdiff.path false &&
 		test_must_fail git difftool ${opt} -y --trust-exit-code -t vimdiff branch
-	"
+	'
 
-	test_expect_success "difftool ${opt:-without options} honors difftool.trustExitCode = true" "
+	test_expect_success "difftool ${opt:-without options} honors difftool.trustExitCode = true" '
 		test_config difftool.error.cmd false &&
 		test_config difftool.trustExitCode true &&
 		test_must_fail git difftool ${opt} -y -t error branch
-	"
+	'
 
-	test_expect_success "difftool ${opt:-without options} honors difftool.trustExitCode = false" "
+	test_expect_success "difftool ${opt:-without options} honors difftool.trustExitCode = false" '
 		test_config difftool.error.cmd false &&
 		test_config difftool.trustExitCode false &&
 		git difftool ${opt} -y -t error branch
-	"
+	'
 
-	test_expect_success "difftool ${opt:-without options} ignores exit code with --no-trust-exit-code" "
+	test_expect_success "difftool ${opt:-without options} ignores exit code with --no-trust-exit-code" '
 		test_config difftool.error.cmd false &&
 		test_config difftool.trustExitCode true &&
 		git difftool ${opt} -y --no-trust-exit-code -t error branch
-	"
+	'
 
-	test_expect_success "difftool ${opt:-without options} stops on error with --trust-exit-code" "
-		test_when_finished 'rm -f for-diff .git/fail-right-file' &&
-		test_when_finished 'git reset -- for-diff' &&
+	test_expect_success "difftool ${opt:-without options} stops on error with --trust-exit-code" '
+		test_when_finished "rm -f for-diff .git/fail-right-file" &&
+		test_when_finished "git reset -- for-diff" &&
 		write_script .git/fail-right-file <<-\EOF &&
 		echo failed
 		exit 1
@@ -138,19 +138,19 @@ do
 		test_must_fail git difftool ${opt} -y --trust-exit-code \
 			--extcmd .git/fail-right-file branch >actual &&
 		test_line_count = 1 actual
-	"
+	'
 
-	test_expect_success "difftool ${opt:-without options} honors exit status if command not found" "
+	test_expect_success "difftool ${opt:-without options} honors exit status if command not found" '
 		test_config difftool.nonexistent.cmd i-dont-exist &&
 		test_config difftool.trustExitCode false &&
-		if test "${opt}" = '--dir-diff'
+		if test "${opt}" = --dir-diff
 		then
 			expected_code=127
 		else
 			expected_code=128
 		fi &&
-		test_expect_code \${expected_code} git difftool ${opt} -y -t nonexistent branch
-	"
+		test_expect_code ${expected_code} git difftool ${opt} -y -t nonexistent branch
+	'
 done
 
 test_expect_success 'difftool honors --gui' '