util/format: add trivial srgb<->linear conversion test

This would've caught 8829f9ccb0 ("u_format: add ETC2 to
util_format_srgb/util_format_linear").

Suggested-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/util/meson.build

@@ -287,4 +287,5 @@ if with_tests
   subdir('tests/vma')
   subdir('tests/set')
   subdir('tests/sparse_array')
+  subdir('tests/format')
 endif

src/util/tests/format/meson.build

@@ -0,0 +1,12 @@
+foreach t : ['srgb']
+  test(t,
+    executable(
+      t,
+      '@0@.c'.format(t),
+      include_directories : inc_common,
+      dependencies : idep_mesautil,
+    ),
+    suite : 'format',
+    should_fail : meson.get_cross_property('xfail', '').contains(t),
+  )
+endforeach

src/util/tests/format/srgb.c

@@ -0,0 +1,40 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "util/macros.h"
+#include "util/format/u_format.h"
+#include "pipe/p_format.h"
+
+int main(void)
+{
+   for (enum pipe_format format = 0; format < PIPE_FORMAT_COUNT; format++)
+   {
+      if (!util_format_is_srgb(format)) {
+         const enum pipe_format linear = util_format_linear(format);
+         if (format != linear) {
+            fprintf(stderr, "%s converted to linear is %s\n",
+                    util_format_name(format),
+                    util_format_name(linear));
+            return EXIT_FAILURE;
+         }
+         continue;
+      }
+
+      const enum pipe_format linear = util_format_linear(format);
+      if (format == linear) {
+         fprintf(stderr, "%s can't be converted to a linear equivalent\n",
+                 util_format_name(format));
+         return EXIT_FAILURE;
+      }
+
+      const enum pipe_format srgb = util_format_srgb(linear);
+      if (format != srgb) {
+         fprintf(stderr, "%s converted to linear and back to srgb becomes %s\n",
+                 util_format_name(format),
+                 util_format_name(srgb));
+         return EXIT_FAILURE;
+      }
+   }
+
+   return EXIT_SUCCESS;
+}