Skip unicode tests for specific VFDs (#5823)

During testing, specific VFDs create files with names that
are different than the "base" filename passed to H5Fcreate().
The unicode tests are setup to expect specific filenames, so
these tests are skipped when the test utility function
h5_fixname() would modify the "base" filename.

Author: jhendersonHDF

test/tunicode.c

@@ -35,6 +35,9 @@
 #define COMP_FLOAT_VAL  (-42.0F)
 #define COMP_DOUBLE_VAL 42.0
 
+/* Size of buffer used for temporary filenames */
+#define TEMP_FILENAME_BUF_SIZE 128
+
 /* Test function prototypes */
 static void test_utf8_filenames(void);
 static void test_utf8_conv_failure(void);
@@ -72,13 +75,29 @@ test_utf8_filenames(void)
     const char *quot_filename = u8"‚.h5"; /* U+201A "Single Low-9 Quotation Mark" */
     const char *chin_filename = u8"漢字.h5";
     hid_t       fid           = H5I_INVALID_HID;
+    hid_t       fapl          = H5I_INVALID_HID;
     char       *env           = NULL;
+    char        fixed_filename[TEMP_FILENAME_BUF_SIZE];
     herr_t      ret;
     int         acc_ret;
 #ifdef H5_HAVE_WIN32_API
     wchar_t *wfilename = NULL;
 #endif
 
+    /*
+     * If the filenames would be perturbed by h5_fixname() due to
+     * a specific VFD being used, skip this test as the filename
+     * could be unpredictable and cause unexpected failures.
+     */
+    fapl = h5_fileaccess();
+    CHECK(fapl, H5I_INVALID_HID, "H5Pcreate");
+    h5_fixname(u8"€", fapl, fixed_filename, TEMP_FILENAME_BUF_SIZE);
+    H5Pclose(fapl);
+    if (0 != strcmp(euro_filename, fixed_filename)) {
+        MESSAGE(5, ("Testing UTF-8 filenames -- SKIPPED due to unpredictable test filenames\n"));
+        return;
+    }
+
     /*
      * If the HDF5_PREFER_WINDOWS_CODE_PAGE environment variable
      * is set to a true value, skip this test as the filenames
@@ -245,10 +264,28 @@ test_utf8_conv_failure(void)
     const char *filename = "\x83\x6E\x83\x8D\x81\x5B\x83\x8F\x81\x5B\x83\x8B\x83\x68"
                            ".h5";
     wchar_t     wfilename[64];
-    hid_t       fid = H5I_INVALID_HID;
+    hid_t       fid  = H5I_INVALID_HID;
+    hid_t       fapl = H5I_INVALID_HID;
+    char        fixed_filename[TEMP_FILENAME_BUF_SIZE];
     herr_t      ret;
     int         int_ret;
 
+    /*
+     * If the filename would be perturbed by h5_fixname() due to
+     * a specific VFD being used, skip this test as the filename
+     * could be unpredictable and cause unexpected failures.
+     */
+    fapl = h5_fileaccess();
+    CHECK(fapl, H5I_INVALID_HID, "H5Pcreate");
+    h5_fixname("\x83\x6E\x83\x8D\x81\x5B\x83\x8F\x81\x5B\x83\x8B\x83\x68", fapl, fixed_filename,
+               TEMP_FILENAME_BUF_SIZE);
+    H5Pclose(fapl);
+    if (0 != strcmp(filename, fixed_filename)) {
+        MESSAGE(5, ("Testing UTF-8 filename conversion failure fallback -- SKIPPED due to unpredictable test "
+                    "filenames\n"));
+        return;
+    }
+
     /*
      * If the current code page would cause a failure in the fallback
      * pathway (for example, if the current code page is UTF-8), skip
@@ -319,12 +356,30 @@ test_utf8_conv_failure(void)
 static void
 test_code_page_override(void)
 {
-    const char *filename = "\xc3\x9f"; /* UTF-8 'ß' / Windows code page 1252 'ß' */
+    const char *filename = "\xc3\x9f"
+                           ".h5"; /* UTF-8 'ß' / Windows code page 1252 'ß' */
     hid_t       fid      = H5I_INVALID_HID;
+    hid_t       fapl     = H5I_INVALID_HID;
     char       *env      = NULL;
+    char        fixed_filename[TEMP_FILENAME_BUF_SIZE];
     herr_t      ret;
     int         int_ret;
 
+    /*
+     * If the filename would be perturbed by h5_fixname() due to
+     * a specific VFD being used, skip this test as the filename
+     * could be unpredictable and cause unexpected failures.
+     */
+    fapl = h5_fileaccess();
+    CHECK(fapl, H5I_INVALID_HID, "H5Pcreate");
+    h5_fixname("\xc3\x9f", fapl, fixed_filename, TEMP_FILENAME_BUF_SIZE);
+    H5Pclose(fapl);
+    if (0 != strcmp(filename, fixed_filename)) {
+        MESSAGE(5, ("Testing code pages environment variable override -- SKIPPED due to unpredictable test "
+                    "filenames"));
+        return;
+    }
+
 #ifdef H5_HAVE_WIN32_API
     /* Perform some initial Windows-specific tests to see if this test
      * needs to be skipped