carbon-lang/diagnostics/diagnostic_emitter_test.cpp

// 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 "diagnostics/diagnostic_emitter.h"

#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/FormatVariadic.h"

namespace Carbon {
namespace {

using ::testing::ElementsAre;
using ::testing::Eq;

struct FakeDiagnostic {
  static constexpr llvm::StringLiteral ShortName = "fake-diagnostic";
  // TODO: consider ways to put the Message into `format` to allow dynamic
  // selection of the message.
  static constexpr llvm::StringLiteral Message = "{0}";

  struct Substitutions {
    std::string message;
  };
  static auto Format(const Substitutions& substitutions) -> std::string {
    // Work around a bug in Clang's unused const variable warning by marking it
    // used here with a no-op.
    static_cast<void>(ShortName);

    return llvm::formatv(Message.data(), substitutions.message).str();
  }
};

TEST(DiagTest, EmitErrors) {
  std::vector<std::string> reported;

  DiagnosticEmitter emitter([&](const Diagnostic& diagnostic) {
    EXPECT_THAT(diagnostic.short_name, Eq("fake-diagnostic"));
    reported.push_back(diagnostic.message);
  });

  emitter.EmitError<FakeDiagnostic>({.message = "M1"});
  emitter.EmitError<FakeDiagnostic>({.message = "M2"});

  EXPECT_THAT(reported, ElementsAre("M1", "M2"));
}

TEST(DiagTest, EmitWarnings) {
  std::vector<std::string> reported;

  DiagnosticEmitter emitter([&](const Diagnostic& diagnostic) {
    EXPECT_THAT(diagnostic.short_name, Eq("fake-diagnostic"));
    reported.push_back(diagnostic.message);
  });

  emitter.EmitWarningIf<FakeDiagnostic>(
      [](FakeDiagnostic::Substitutions& diagnostic) {
        diagnostic.message = "M1";
        return true;
      });
  emitter.EmitWarningIf<FakeDiagnostic>(
      [](FakeDiagnostic::Substitutions& diagnostic) {
        diagnostic.message = "M2";
        return false;
      });
  emitter.EmitWarningIf<FakeDiagnostic>(
      [](FakeDiagnostic::Substitutions& diagnostic) {
        diagnostic.message = "M3";
        return true;
      });

  EXPECT_THAT(reported, ElementsAre("M1", "M3"));
}

}  // namespace
}  // namespace Carbon