testsuite: Add render tests for all the empty nodes

Test that rendering empty nodes succees. For a lot of nodes the
resulting rendering isn't clearly defined, in those cases we overdraw
those regions (sometimes the whole image) with black.

testsuite/gsk/compare/empty-blend.node

@@ -0,0 +1 @@
+blend { }

testsuite/gsk/compare/empty-blur.node

@@ -0,0 +1,20 @@
+blur { }
+
+/* The blur algorithm isn't specified, so
+   don't test it. */
+color {
+  bounds: -3 -3 50 6;
+  color: black;
+}
+color {
+  bounds: 47 -3 6 50;
+  color: black;
+}
+color {
+  bounds: 3 47 50 6;
+  color: black;
+}
+color {
+  bounds: -3 3 6 50;
+  color: black;
+}

testsuite/gsk/compare/empty-border.node

@@ -0,0 +1 @@
+border { }

testsuite/gsk/compare/empty-clip.node

@@ -0,0 +1 @@
+clip { }

testsuite/gsk/compare/empty-color-matrix.node

@@ -0,0 +1 @@
+color-matrix { }

testsuite/gsk/compare/empty-color.node

@@ -0,0 +1 @@
+color { }

testsuite/gsk/compare/empty-container.node

@@ -0,0 +1,8 @@
+container { }
+
+/* We need to contain something because 0x0 nodes
+   cause NULL textures */
+color {
+  bounds: -1 -1 1 1;
+  color: transparent;
+}

testsuite/gsk/compare/empty-cross-fade.node

@@ -0,0 +1,9 @@
+cross-fade { }
+
+/* This is not very useful as a test, because the
+   resulting color is undefined, because 0.5 * 255
+   can be rounded to either 127 or 128 by the renderers.
+   But at least we know they get the size right... */
+color {
+  color: black;
+}

testsuite/gsk/compare/empty-debug.node

@@ -0,0 +1 @@
+debug { }

testsuite/gsk/compare/empty-inset-shadow.node

@@ -0,0 +1 @@
+inset-shadow { }

testsuite/gsk/compare/empty-linear-gradient.node

@@ -0,0 +1 @@
+linear-gradient { }

testsuite/gsk/compare/empty-opacity.node

@@ -0,0 +1,9 @@
+opacity { }
+
+/* This is not very useful as a test, because the
+   resulting color is undefined, because 0.5 * 255
+   can be rounded to either 127 or 128 by the renderers.
+   But at least we know they get the size right... */
+color {
+  color: black;
+}

testsuite/gsk/compare/empty-outset-shadow.node

@@ -0,0 +1 @@
+outset-shadow { }

testsuite/gsk/compare/empty-repeat.node

@@ -0,0 +1 @@
+repeat { }

testsuite/gsk/compare/empty-rounded-clip.node

@@ -0,0 +1 @@
+rounded-clip { }

testsuite/gsk/compare/empty-shadow.node

@@ -0,0 +1 @@
+shadow { }

testsuite/gsk/compare/empty-text.node

@@ -0,0 +1 @@
+text { }

testsuite/gsk/compare/empty-texture.node

@@ -0,0 +1,12 @@
+texture { }
+
+/* The bilinear filtering code can differ
+   between implementations, so cover it */
+color {
+  bounds: 21 0 10 50;
+  color: black;
+}
+color {
+  bounds: 0 21 50 10;
+  color: black;
+}

testsuite/gsk/compare/empty-transform.node

@@ -0,0 +1 @@
+transform { }

testsuite/gsk/meson.build

@@ -32,6 +32,25 @@ compare_render_tests = [
   'clipped_rounded_clip',
   'color-blur0',
   'cross-fade-in-opacity',
+  'empty-blend',
+  'empty-blur',
+  'empty-border',
+  'empty-clip',
+  'empty-color',
+  'empty-color-matrix',
+  'empty-container',
+  'empty-cross-fade',
+  'empty-debug',
+  'empty-inset-shadow',
+  'empty-linear-gradient',
+  'empty-opacity',
+  'empty-outset-shadow',
+  'empty-repeat',
+  'empty-rounded-clip',
+  'empty-shadow',
+  'empty-text',
+  'empty-texture',
+  'empty-transform',
   'opacity_clip',
   'outset_shadow_offset_both',
   'outset_shadow_offset_x',