Enable basic tests for D3D12

src/tests/NXTTest.cpp

@@ -278,6 +278,8 @@ namespace detail {
     bool IsBackendAvailable(BackendType type) {
         #if defined(__APPLE__)
             return type == MetalBackend;
+        #elif defined(_WIN32)
+            return type == D3D12Backend;
         #else
             return false;
         #endif

src/tests/end2end/BasicTests.cpp

@@ -56,4 +56,4 @@ TEST_P(BasicTests, ReadPixelsTest) {
     EXPECT_PIXEL_RGBA8_EQ(red, texture, 0, 0);
 }
 
-NXT_INSTANTIATE_TEST(BasicTests, MetalBackend)
+NXT_INSTANTIATE_TEST(BasicTests, MetalBackend, D3D12Backend)