Add DepthStencilState validation unit tests

src/tests/CMakeLists.txt

diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index 0b4ced3..b79d00b 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -26,6 +26,7 @@
     ${UNITTESTS_DIR}/ToBackendTests.cpp
     ${UNITTESTS_DIR}/WireTests.cpp
     ${VALIDATION_TESTS_DIR}/BufferValidationTest.cpp
+    ${VALIDATION_TESTS_DIR}/DepthStencilStateValidationTest.cpp
     ${VALIDATION_TESTS_DIR}/ValidationTest.cpp
     ${VALIDATION_TESTS_DIR}/ValidationTest.h
     ${TESTS_DIR}/UnittestsMain.cpp

src/tests/unittests/validation/DepthStencilStateValidationTest.cpp

diff --git a/src/tests/unittests/validation/DepthStencilStateValidationTest.cpp b/src/tests/unittests/validation/DepthStencilStateValidationTest.cpp
new file mode 100644
index 0000000..c7b6c40
--- /dev/null
+++ b/src/tests/unittests/validation/DepthStencilStateValidationTest.cpp
@@ -0,0 +1,82 @@
+// Copyright 2017 The NXT Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "ValidationTest.h"
+
+class DepthStencilStateValidationTest : public ValidationTest {
+};
+
+TEST_F(DepthStencilStateValidationTest, Creation) {
+    // Success
+    nxt::DepthStencilState buf0 = AssertWillBeSuccess(device.CreateDepthStencilStateBuilder())
+        .SetDepthCompareFunction(nxt::CompareFunction::Less)
+        .SetDepthWriteEnabled(true)
+        .SetStencilFunction(nxt::Face::Both, nxt::CompareFunction::Greater,
+            nxt::StencilOperation::Keep, nxt::StencilOperation::Keep, nxt::StencilOperation::Replace)
+        .SetStencilMask(nxt::Face::Both, 0x1)
+        .GetResult();
+
+    // Success for empty builder
+    nxt::DepthStencilState buf1 = AssertWillBeSuccess(device.CreateDepthStencilStateBuilder())
+        .GetResult();
+
+    // Test failure when specifying properties multiple times
+    nxt::DepthStencilState buf2 = AssertWillBeError(device.CreateDepthStencilStateBuilder())
+        .SetDepthWriteEnabled(true)
+        .SetDepthWriteEnabled(false)
+        .GetResult();
+
+    nxt::DepthStencilState buf3 = AssertWillBeError(device.CreateDepthStencilStateBuilder())
+        .SetDepthCompareFunction(nxt::CompareFunction::Less)
+        .SetDepthCompareFunction(nxt::CompareFunction::Greater)
+        .GetResult();
+
+    // Test success when setting properties on separate faces
+    nxt::DepthStencilState buf4 = AssertWillBeSuccess(device.CreateDepthStencilStateBuilder())
+        .SetStencilMask(nxt::Face::Front, 0x00)
+        .SetStencilMask(nxt::Face::Back, 0xff)
+        .GetResult();
+
+    nxt::DepthStencilState buf5 = AssertWillBeSuccess(device.CreateDepthStencilStateBuilder())
+        .SetStencilFunction(nxt::Face::Front, nxt::CompareFunction::Less,
+            nxt::StencilOperation::Replace, nxt::StencilOperation::Replace, nxt::StencilOperation::Replace)
+        .SetStencilFunction(nxt::Face::Back, nxt::CompareFunction::Greater,
+            nxt::StencilOperation::Replace, nxt::StencilOperation::Replace, nxt::StencilOperation::Replace)
+        .GetResult();
+
+    // Test failure when setting properties on a face multiple times
+    nxt::DepthStencilState buf6 = AssertWillBeError(device.CreateDepthStencilStateBuilder())
+        .SetStencilMask(nxt::Face::Back, 0x00)
+        .SetStencilMask(nxt::Face::Back, 0xff)
+        .GetResult();
+
+    nxt::DepthStencilState buf7 = AssertWillBeError(device.CreateDepthStencilStateBuilder())
+        .SetStencilFunction(nxt::Face::Back, nxt::CompareFunction::Less,
+            nxt::StencilOperation::Replace, nxt::StencilOperation::Replace, nxt::StencilOperation::Replace)
+        .SetStencilFunction(nxt::Face::Back, nxt::CompareFunction::Greater,
+            nxt::StencilOperation::Replace, nxt::StencilOperation::Replace, nxt::StencilOperation::Replace)
+        .GetResult();
+
+    nxt::DepthStencilState buf8 = AssertWillBeError(device.CreateDepthStencilStateBuilder())
+        .SetStencilMask(nxt::Face::Both, 0x00)
+        .SetStencilMask(nxt::Face::Back, 0xff)
+        .GetResult();
+
+    nxt::DepthStencilState buf9 = AssertWillBeError(device.CreateDepthStencilStateBuilder())
+        .SetStencilFunction(nxt::Face::Both, nxt::CompareFunction::Less,
+            nxt::StencilOperation::Replace, nxt::StencilOperation::Replace, nxt::StencilOperation::Replace)
+        .SetStencilFunction(nxt::Face::Back, nxt::CompareFunction::Greater,
+            nxt::StencilOperation::Replace, nxt::StencilOperation::Replace, nxt::StencilOperation::Replace)
+        .GetResult();
+}