[ir] Add store test

This CL adds a simple test for the builder_impl for assignments.

Bug: tint:1718
Change-Id: Ia727ace4d01f107c6ac2ad1f8e430ef00ec43da9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/131660
Auto-Submit: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: James Price <jrprice@google.com>

src/tint/BUILD.gn

@@ -2149,6 +2149,7 @@ if (tint_build_unittests) {
       "ir/builder_impl_call_test.cc",
       "ir/builder_impl_literal_test.cc",
       "ir/builder_impl_materialize_test.cc",
+      "ir/builder_impl_store_test.cc",
       "ir/builder_impl_test.cc",
       "ir/builder_impl_unary_test.cc",
       "ir/builder_impl_var_test.cc",

src/tint/CMakeLists.txt

@@ -1446,6 +1446,7 @@ if(TINT_BUILD_TESTS)
       ir/builder_impl_call_test.cc
       ir/builder_impl_literal_test.cc
       ir/builder_impl_materialize_test.cc
+      ir/builder_impl_store_test.cc
       ir/builder_impl_test.cc
       ir/builder_impl_unary_test.cc
       ir/builder_impl_var_test.cc

src/tint/ir/builder_impl_store_test.cc

@@ -0,0 +1,54 @@
+// Copyright 2023 The Tint 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 "src/tint/ir/test_helper.h"
+
+#include "gmock/gmock.h"
+#include "src/tint/ast/case_selector.h"
+#include "src/tint/ast/int_literal_expression.h"
+#include "src/tint/constant/scalar.h"
+
+namespace tint::ir {
+namespace {
+
+using namespace tint::number_suffixes;  // NOLINT
+
+using IR_BuilderImplTest = TestHelper;
+
+TEST_F(IR_BuilderImplTest, EmitStatement_Assign) {
+    GlobalVar("a", ty.u32(), builtin::AddressSpace::kPrivate);
+
+    auto* expr = Assign("a", 4_u);
+    WrapInFunction(expr);
+
+    auto r = Build();
+    ASSERT_TRUE(r) << Error();
+    auto m = r.Move();
+
+    EXPECT_EQ(Disassemble(m), R"(%fn0 = block
+%1:ref<private, u32, read_write> = var private read_write
+
+
+
+%fn1 = func test_function():void [@compute @workgroup_size(1, 1, 1)]
+  %fn2 = block
+  store %1:ref<private, u32, read_write>, 4u
+  ret
+func_end
+
+)");
+}
+
+}  // namespace
+}  // namespace tint::ir