Starting to think about toolchain semantic analysis -- create a trivial shell for it. (#1038)

toolchain/semantics/semantics_test.cpp

@@ -0,0 +1,42 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include "toolchain/semantics/semantics.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <optional>
+
+#include "toolchain/diagnostics/diagnostic_emitter.h"
+#include "toolchain/lexer/tokenized_buffer.h"
+#include "toolchain/parser/parse_tree.h"
+#include "toolchain/source/source_buffer.h"
+
+namespace Carbon::Testing {
+namespace {
+
+class ParseTreeTest : public ::testing::Test {
+ protected:
+  auto Analyze(llvm::Twine t) -> Semantics {
+    source_buffer.emplace(SourceBuffer::CreateFromText(t.str()));
+    tokenized_buffer = TokenizedBuffer::Lex(*source_buffer, consumer);
+    parse_tree = ParseTree::Parse(*tokenized_buffer, consumer);
+    return Semantics::Analyze(*parse_tree, consumer);
+  }
+
+  std::optional<SourceBuffer> source_buffer;
+  std::optional<TokenizedBuffer> tokenized_buffer;
+  std::optional<ParseTree> parse_tree;
+  DiagnosticConsumer& consumer = ConsoleDiagnosticConsumer();
+};
+
+TEST_F(ParseTreeTest, Empty) {
+  // TODO: Validate the returned Semantics object.
+  Analyze("");
+  ASSERT_FALSE(parse_tree->HasErrors());
+}
+
+}  // namespace
+}  // namespace Carbon::Testing