test: add some path handling tests

Exhaustive tests would be nice, but I'm only adding a test for a
function I'm going to change.

test/paths.c

@@ -0,0 +1,48 @@
+#include "common/common.h"
+#include "config.h"
+#include "options/path.h"
+#include "tests.h"
+
+static void test_join(char *file, int line, char *a, char *b, char *c)
+{
+    char *res = mp_path_join(NULL, a, b);
+    if (strcmp(res, c) != 0) {
+        printf("%s:%d: '%s' + '%s' = '%s', expected '%s'\n", file, line,
+               a, b, res, c);
+        abort();
+    }
+    talloc_free(res);
+}
+
+#define TEST_JOIN(a, b, c) \
+    test_join(__FILE__, __LINE__, a, b, c);
+
+static void run(struct test_ctx *ctx)
+{
+    TEST_JOIN("",           "",             "");
+    TEST_JOIN("a",          "",             "a");
+    TEST_JOIN("/a",         "",             "/a");
+    TEST_JOIN("",           "b",            "b");
+    TEST_JOIN("",           "/b",           "/b");
+    TEST_JOIN("ab",         "cd",           "ab/cd");
+    TEST_JOIN("ab/",        "cd",           "ab/cd");
+    TEST_JOIN("ab/",        "/cd",          "/cd");
+    // Note: we prefer "/" on win32, but tolerate "\".
+#if HAVE_DOS_PATHS
+    TEST_JOIN("ab\\",       "cd",           "ab\\cd");
+    TEST_JOIN("ab\\",       "\\cd",         "\\cd");
+    TEST_JOIN("c:/",        "de",           "c:/de");
+    TEST_JOIN("c:/a",       "de",           "c:/a/de");
+    TEST_JOIN("c:\\a",      "c:\\b",        "c:\\b");
+    TEST_JOIN("c:/a",       "c:/b",         "c:/b");
+    // Note: drive-relative paths are not always supported "properly"
+    TEST_JOIN("c:/a",       "d:b",          "d:b");
+    TEST_JOIN("c:a",        "b",            "c:a/b");
+    TEST_JOIN("c:",         "b",            "c:b");
+#endif
+}
+
+const struct unittest test_paths = {
+    .name = "paths",
+    .run = run,
+};

test/tests.c

@@ -9,6 +9,7 @@ static const struct unittest *unittests[] = {
     &test_img_format,
     &test_json,
     &test_linked_list,
+    &test_paths,
     &test_repack_sws,
 #if HAVE_ZIMG
     &test_repack_zimg,

test/tests.h

@@ -43,6 +43,7 @@ extern const struct unittest test_json;
 extern const struct unittest test_linked_list;
 extern const struct unittest test_repack_sws;
 extern const struct unittest test_repack_zimg;
+extern const struct unittest test_paths;
 
 #define assert_true(x) assert(x)
 #define assert_false(x) assert(!(x))

wscript_build.py

@@ -403,6 +403,7 @@ def build(ctx):
         ( "test/img_format.c",                   "tests" ),
         ( "test/json.c",                         "tests" ),
         ( "test/linked_list.c",                  "tests" ),
+        ( "test/paths.c",                        "tests" ),
         ( "test/scale_sws.c",                    "tests" ),
         ( "test/scale_test.c",                   "tests" ),
         ( "test/scale_zimg.c",                   "tests && zimg" ),