1 files changed, 55 insertions, 0 deletions
diff --git a/clang-tools-extra/unittests/clangd/GlobalCompilationDatabaseTests.cpp b/clang-tools-extra/unittests/clangd/GlobalCompilationDatabaseTests.cpp
index 5e2dfab596c..f938b302b66 100644
--- a/clang-tools-extra/unittests/clangd/GlobalCompilationDatabaseTests.cpp
+++ b/clang-tools-extra/unittests/clangd/GlobalCompilationDatabaseTests.cpp
@@ -33,6 +33,61 @@ TEST(GlobalCompilationDatabaseTest, FallbackCommand) {
                                            testPath("foo/bar.h")));
 }
 
+static tooling::CompileCommand cmd(StringRef File, StringRef Arg) {
+  return tooling::CompileCommand(testRoot(), File, {"clang", Arg, File}, "");
+}
+
+class OverlayCDBTest : public ::testing::Test {
+  class BaseCDB : public GlobalCompilationDatabase {
+  public:
+    Optional<tooling::CompileCommand>
+    getCompileCommand(StringRef File) const override {
+      if (File == testPath("foo.cc"))
+        return cmd(File, "-DA=1");
+      return None;
+    }
+
+    tooling::CompileCommand getFallbackCommand(StringRef File) const override {
+      return cmd(File, "-DA=2");
+    }
+  };
+
+protected:
+  OverlayCDBTest() : Base(llvm::make_unique<BaseCDB>()) {}
+  std::unique_ptr<GlobalCompilationDatabase> Base;
+};
+
+TEST_F(OverlayCDBTest, GetCompileCommand) {
+  OverlayCDB CDB(Base.get());
+  EXPECT_EQ(CDB.getCompileCommand(testPath("foo.cc")),
+            Base->getCompileCommand(testPath("foo.cc")));
+  EXPECT_EQ(CDB.getCompileCommand(testPath("missing.cc")), llvm::None);
+
+  auto Override = cmd(testPath("foo.cc"), "-DA=3");
+  CDB.setCompileCommand(testPath("foo.cc"), Override);
+  EXPECT_EQ(CDB.getCompileCommand(testPath("foo.cc")), Override);
+  EXPECT_EQ(CDB.getCompileCommand(testPath("missing.cc")), llvm::None);
+  CDB.setCompileCommand(testPath("missing.cc"), Override);
+  EXPECT_EQ(CDB.getCompileCommand(testPath("missing.cc")), Override);
+}
+
+TEST_F(OverlayCDBTest, GetFallbackCommand) {
+  OverlayCDB CDB(Base.get(), {"-DA=4"});
+  EXPECT_THAT(CDB.getFallbackCommand(testPath("bar.cc")).CommandLine,
+              ElementsAre("clang", "-DA=2", testPath("bar.cc"), "-DA=4"));
+}
+
+TEST_F(OverlayCDBTest, NoBase) {
+  OverlayCDB CDB(nullptr, {"-DA=6"});
+  EXPECT_EQ(CDB.getCompileCommand(testPath("bar.cc")), None);
+  auto Override = cmd(testPath("bar.cc"), "-DA=5");
+  CDB.setCompileCommand(testPath("bar.cc"), Override);
+  EXPECT_EQ(CDB.getCompileCommand(testPath("bar.cc")), Override);
+
+  EXPECT_THAT(CDB.getFallbackCommand(testPath("foo.cc")).CommandLine,
+              ElementsAre("clang", testPath("foo.cc"), "-DA=6"));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang