testsuite: Make nodeparser use shared diffing code

We have a testutils.c version, use that one.

testsuite/gsk/meson.build

@@ -4,7 +4,8 @@ compare_render = executable('compare-render',
   c_args: common_cflags + ['-DGTK_COMPILATION'],
 )
 
-node_parser = executable('node-parser', 'node-parser.c',
+node_parser = executable('node-parser', 
+  [ 'node-parser.c', '../testutils.c' ],
   dependencies: libgtk_dep,
   c_args: common_cflags,
 )

testsuite/gsk/node-parser.c

@@ -22,6 +22,8 @@
 
 #include <gtk/gtk.h>
 
+#include "../testutils.h"
+
 static char *
 test_get_reference_file (const char *node_file)
 {
@@ -64,47 +66,6 @@ test_get_errors_file (const char *node_file)
   return g_string_free (file, FALSE);
 }
 
-static GBytes *
-diff_with_file (const char  *file1,
-                GBytes      *input,
-                GError     **error)
-{
-  GSubprocess *process;
-  GBytes *output;
-
-  process = g_subprocess_new (G_SUBPROCESS_FLAGS_STDIN_PIPE
-                              | G_SUBPROCESS_FLAGS_STDOUT_PIPE,
-                              error,
-                              "diff", "--strip-trailing-cr", "-u", file1, "-", NULL);
-  if (process == NULL)
-    return NULL;
-
-  if (!g_subprocess_communicate (process,
-                                 input,
-                                 NULL,
-                                 &output,
-                                 NULL,
-                                 error))
-    {
-      g_object_unref (process);
-      return NULL;
-    }
-
-  if (!g_subprocess_get_successful (process) &&
-      /* this is the condition when the files differ */
-      !(g_subprocess_get_if_exited (process) && g_subprocess_get_exit_status (process) == 1))
-    {
-      g_clear_pointer (&output, g_bytes_unref);
-      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
-                   "The `diff' process exited with error status %d",
-                   g_subprocess_get_exit_status (process));
-    }
-
-  g_object_unref (process);
-
-  return output;
-}
-
 static void
 append_error_value (GString *string,
                     GType    enum_type,
@@ -162,8 +123,9 @@ parse_node_file (GFile *file, gboolean generate)
   char *node_file, *reference_file, *errors_file;
   GskRenderNode *node;
   GString *errors;
-  GBytes *diff, *bytes;
+  GBytes *bytes;
   GError *error = NULL;
+  char *diff;
   gboolean result = TRUE;
 
   bytes = g_file_load_bytes (file, NULL, NULL, &error);
@@ -193,33 +155,33 @@ parse_node_file (GFile *file, gboolean generate)
   node_file = g_file_get_path (file);
   reference_file = test_get_reference_file (node_file);
 
-  diff = diff_with_file (reference_file, bytes, &error);
+  diff = diff_bytes_with_file (reference_file, bytes, &error);
   g_assert_no_error (error);
 
-  if (diff && g_bytes_get_size (diff) > 0)
+  if (diff)
     {
       g_print ("Resulting file doesn't match reference:\n%s\n",
-               (const char *) g_bytes_get_data (diff, NULL));
+               (const char *) diff);
       result = FALSE;
     }
   g_free (reference_file);
-  g_clear_pointer (&diff, g_bytes_unref);
+  g_clear_pointer (&diff, g_free);
 
   errors_file = test_get_errors_file (node_file);
 
   if (errors_file)
     {
       GBytes *error_bytes = g_string_free_to_bytes (errors);
-      diff = diff_with_file (errors_file, error_bytes, &error);
+      diff = diff_bytes_with_file (errors_file, error_bytes, &error);
       g_assert_no_error (error);
 
-      if (diff && g_bytes_get_size (diff) > 0)
+      if (diff)
         {
           g_print ("Errors don't match expected errors:\n%s\n",
-                   (const char *) g_bytes_get_data (diff, NULL));
+                   (const char *) diff);
           result = FALSE;
         }
-      g_clear_pointer (&diff, g_bytes_unref);
+      g_clear_pointer (&diff, g_free);
       g_clear_pointer (&error_bytes, g_bytes_unref);
     }
   else if (errors->str[0])