testsuite: Improve diff_with_file() function

Properly handle diff(1) failing.

In this particular case, the test passed a NULL input file to the diff
(that was fixed, too) and then diff only found one input file and
aborted.

But without this fix, we'd also not catch other abortion reasons for
diff() - as long as it exited in any way, we were happy.

testsuite/css/parser/test-css-parser.c

@@ -101,6 +101,16 @@ diff_with_file (const char  *file1,
       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);
   g_bytes_unref (input);
 

testsuite/css/style/test-css-style.c

@@ -50,52 +50,49 @@ test_get_other_file (const char *ui_file, const char *extension)
   return g_string_free (file, FALSE);
 }
 
-static char *
+static GBytes *
 diff_with_file (const char  *file1,
                 char        *text,
                 gssize       len,
                 GError     **error)
 {
-  const char *command[] = { "diff", "-u", file1, NULL, NULL };
-  char *diff, *tmpfile;
-  int fd;
+  GSubprocess *process;
+  GBytes *input, *output;
 
-  diff = NULL;
-
-  if (len < 0)
-    len = strlen (text);
-  
-  /* write the text buffer to a temporary file */
-  fd = g_file_open_tmp (NULL, &tmpfile, error);
-  if (fd < 0)
+  process = g_subprocess_new (G_SUBPROCESS_FLAGS_STDIN_PIPE
+                              | G_SUBPROCESS_FLAGS_STDOUT_PIPE,
+                              error,
+                              "diff", "-u", file1, "-", NULL);
+  if (process == NULL)
     return NULL;
 
-  if (write (fd, text, len) != (int) len)
+  input = g_bytes_new_static (text, len >= 0 ? len : strlen (text));
+  if (!g_subprocess_communicate (process,
+                                 input,
+                                 NULL,
+                                 &output,
+                                 NULL,
+                                 error))
     {
-      close (fd);
-      g_set_error (error,
-                   G_FILE_ERROR, G_FILE_ERROR_FAILED,
-                   "Could not write data to temporary file '%s'", tmpfile);
-      goto done;
+      g_object_unref (process);
+      g_bytes_unref (input);
+      return NULL;
     }
-  close (fd);
-  command[3] = tmpfile;
 
-  /* run diff command */
-  g_spawn_sync (NULL, 
-                (char **) command,
-                NULL,
-                G_SPAWN_SEARCH_PATH,
-                NULL, NULL,
-	        &diff,
-                NULL, NULL,
-                error);
+  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));
+    }
 
-done:
-  g_unlink (tmpfile);
-  g_free (tmpfile);
+  g_object_unref (process);
+  g_bytes_unref (input);
 
-  return diff;
+  return output;
 }
 
 static void
@@ -115,7 +112,8 @@ load_ui_file (GFile *file, gboolean generate)
 {
   GtkBuilder *builder;
   GtkWidget *window;
-  char *output, *diff;
+  char *output;
+  GBytes *diff;
   char *ui_file, *css_file, *reference_file;
   GtkCssProvider *provider;
   GError *error = NULL;
@@ -151,17 +149,18 @@ load_ui_file (GFile *file, gboolean generate)
     }
 
   reference_file = test_get_other_file (ui_file, ".nodes");
+  g_assert (reference_file != NULL);
 
   diff = diff_with_file (reference_file, output, -1, &error);
   g_assert_no_error (error);
 
-  if (diff && diff[0])
+  if (diff && g_bytes_get_size (diff) > 0)
     {
-      g_test_message ("Resulting output doesn't match reference:\n%s", diff);
+      g_test_message ("Resulting output doesn't match reference:\n%s", (const char *) g_bytes_get_data (diff, NULL));
       g_test_fail ();
     }
   g_free (reference_file);
-  g_free (diff);
+  g_clear_pointer (&diff, g_bytes_unref);
 
 out:
   gtk_style_context_remove_provider_for_display (gdk_display_get_default (),

testsuite/gsk/node-parser.c

@@ -90,6 +90,16 @@ diff_with_file (const char  *file1,
       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;