Fix framebuffer dimensions in InputStateTest

Also add validation that the framebuffer size matches its attachement
size and make a test for it.

src/backend/Framebuffer.cpp

@@ -75,6 +75,14 @@ namespace backend {
                     return nullptr;
                 }
                 usingBackbufferHack = true;
+                continue;
+            }
+
+            // TODO(cwallez@chromium.org): Adjust for the mip-level once that is supported.
+            if (textureView->GetTexture()->GetWidth() != width ||
+                textureView->GetTexture()->GetHeight() != height) {
+                HandleError("Framebuffer size doesn't match attachment size");
+                return nullptr;
             }
         }
 

src/tests/end2end/InputStateTests.cpp

@@ -58,7 +58,7 @@ class InputStateTest : public NXTTest {
             framebuffer = device.CreateFramebufferBuilder()
                 .SetRenderPass(renderpass)
                 .SetAttachment(0, renderTargetView)
-                .SetDimensions(640, 480)
+                .SetDimensions(400, 400)
                 .GetResult();
         }
 
@@ -199,7 +199,7 @@ class InputStateTest : public NXTTest {
             }
 
             nxt::CommandBuffer commands = builder
-                .DrawArrays(triangles * 4, instances, 0, 0)
+                .DrawArrays(triangles * 3, instances, 0, 0)
                 .EndRenderSubpass()
                 .EndRenderPass()
                 .GetResult();

src/tests/unittests/validation/FramebufferValidationTests.cpp

@@ -15,6 +15,20 @@
 #include "tests/unittests/validation/ValidationTest.h"
 
 class FramebufferValidationTest : public ValidationTest {
+    protected:
+        nxt::TextureView Create2DAttachment(uint32_t width, uint32_t height, nxt::TextureFormat format) {
+            nxt::Texture attachment = device.CreateTextureBuilder()
+                .SetDimension(nxt::TextureDimension::e2D)
+                .SetExtent(width, height, 1)
+                .SetFormat(format)
+                .SetMipLevels(1)
+                .SetAllowedUsage(nxt::TextureUsageBit::OutputAttachment)
+                .SetInitialUsage(nxt::TextureUsageBit::OutputAttachment)
+                .GetResult();
+
+            return attachment.CreateTextureViewBuilder()
+                .GetResult();
+        }
 };
 
 // Test for an empty framebuffer builder
@@ -64,3 +78,46 @@ TEST_F(FramebufferValidationTest, BasicWithEmptyAttachment) {
         .SetDimensions(100, 100)
         .GetResult();
 }
+
+// Check validation that the attachment size must be the same as the framebuffer size.
+// TODO(cwallez@chromium.org): Investigate this constraint more, for example Vulkan requires
+// that the attachment sizes are *at least* the framebuffer size.
+TEST_F(FramebufferValidationTest, AttachmentSizeMatchFramebufferSize) {
+    auto renderpass = AssertWillBeSuccess(device.CreateRenderPassBuilder())
+        .SetAttachmentCount(1)
+        .AttachmentSetFormat(0, nxt::TextureFormat::R8G8B8A8Unorm)
+        .SetSubpassCount(1)
+        .SubpassSetColorAttachment(0, 0, 0)
+        .GetResult();
+
+    nxt::TextureView attachment = Create2DAttachment(100, 100, nxt::TextureFormat::R8G8B8A8Unorm);
+
+    // Control case: two attachments of the same size
+    {
+        auto framebuffer = AssertWillBeSuccess(device.CreateFramebufferBuilder())
+            .SetRenderPass(renderpass)
+            .SetAttachment(0, attachment)
+            .SetDimensions(100, 100)
+            .GetResult();
+    }
+
+    // Error: case, size mismatch (framebuffer bigger than attachments)
+    {
+        auto framebuffer = AssertWillBeError(device.CreateFramebufferBuilder())
+            .SetRenderPass(renderpass)
+            .SetAttachment(0, attachment)
+            .SetDimensions(200, 200)
+            .GetResult();
+    }
+
+    // Error: case, size mismatch (framebuffer smaller than attachments)
+    {
+        auto framebuffer = AssertWillBeError(device.CreateFramebufferBuilder())
+            .SetRenderPass(renderpass)
+            .SetAttachment(0, attachment)
+            .SetDimensions(50, 50)
+            .GetResult();
+    }
+
+    // TODO(cwallez@chromium.org): also test with a mismatches depth / stencil
+}