is_{hfs,ntfs}_dotgitmodules: add tests

This tests primarily for NTFS issues, but also adds one example of an
HFS+ issue.

Thanks go to Congyi Wu for coming up with the list of examples where
NTFS would possibly equate the filename with `.gitmodules`.
Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJeff King <peff@peff.net>

t/helper/test-path-utils.c

 #include "cache.h"
 #include "string-list.h"
+#include "utf8.h"
 
 /*
  * A "string_list_each_func_t" function that normalizes an entry from
@@ -156,6 +157,11 @@ static struct test_data dirname_data[] = {
 	{ NULL,              NULL     }
 };
 
+static int is_dotgitmodules(const char *path)
+{
+	return is_hfs_dotgitmodules(path) || is_ntfs_dotgitmodules(path);
+}
+
 int cmd_main(int argc, const char **argv)
 {
 	if (argc == 3 && !strcmp(argv[1], "normalize_path_copy")) {
@@ -256,6 +262,20 @@ int cmd_main(int argc, const char **argv)
 	if (argc == 2 && !strcmp(argv[1], "dirname"))
 		return test_function(dirname_data, dirname, argv[1]);
 
+	if (argc > 2 && !strcmp(argv[1], "is_dotgitmodules")) {
+		int res = 0, expect = 1, i;
+		for (i = 2; i < argc; i++)
+			if (!strcmp("--not", argv[i]))
+				expect = !expect;
+			else if (expect != is_dotgitmodules(argv[i]))
+				res = error("'%s' is %s.gitmodules", argv[i],
+					    expect ? "not " : "");
+			else
+				fprintf(stderr, "ok: '%s' is %s.gitmodules\n",
+					argv[i], expect ? "" : "not ");
+		return !!res;
+	}
+
 	fprintf(stderr, "%s: unknown function name: %s\n", argv[0],
 		argv[1] ? argv[1] : "(there was none)");
 	return 1;

t/t0060-path-utils.sh

@@ -349,4 +349,90 @@ test_submodule_relative_url "(null)" "ssh://hostname:22/repo" "../subrepo" "ssh:
 test_submodule_relative_url "(null)" "user@host:path/to/repo" "../subrepo" "user@host:path/to/subrepo"
 test_submodule_relative_url "(null)" "user@host:repo" "../subrepo" "user@host:subrepo"
 
+test_expect_success 'match .gitmodules' '
+	test-path-utils is_dotgitmodules \
+		.gitmodules \
+		\
+		.git${u200c}modules \
+		\
+		.Gitmodules \
+		.gitmoduleS \
+		\
+		".gitmodules " \
+		".gitmodules." \
+		".gitmodules  " \
+		".gitmodules. " \
+		".gitmodules ." \
+		".gitmodules.." \
+		".gitmodules   " \
+		".gitmodules.  " \
+		".gitmodules . " \
+		".gitmodules  ." \
+		\
+		".Gitmodules " \
+		".Gitmodules." \
+		".Gitmodules  " \
+		".Gitmodules. " \
+		".Gitmodules ." \
+		".Gitmodules.." \
+		".Gitmodules   " \
+		".Gitmodules.  " \
+		".Gitmodules . " \
+		".Gitmodules  ." \
+		\
+		GITMOD~1 \
+		gitmod~1 \
+		GITMOD~2 \
+		gitmod~3 \
+		GITMOD~4 \
+		\
+		"GITMOD~1 " \
+		"gitmod~2." \
+		"GITMOD~3  " \
+		"gitmod~4. " \
+		"GITMOD~1 ." \
+		"gitmod~2   " \
+		"GITMOD~3.  " \
+		"gitmod~4 . " \
+		\
+		GI7EBA~1 \
+		gi7eba~9 \
+		\
+		GI7EB~10 \
+		GI7EB~11 \
+		GI7EB~99 \
+		GI7EB~10 \
+		GI7E~100 \
+		GI7E~101 \
+		GI7E~999 \
+		~1000000 \
+		~9999999 \
+		\
+		--not \
+		".gitmodules x"  \
+		".gitmodules .x" \
+		\
+		" .gitmodules" \
+		\
+		..gitmodules \
+		\
+		gitmodules \
+		\
+		.gitmodule \
+		\
+		".gitmodules x " \
+		".gitmodules .x" \
+		\
+		GI7EBA~ \
+		GI7EBA~0 \
+		GI7EBA~~1 \
+		GI7EBA~X \
+		Gx7EBA~1 \
+		GI7EBX~1 \
+		\
+		GI7EB~1 \
+		GI7EB~01 \
+		GI7EB~1X
+'
+
 test_done