src/developer/debug/zxdb/expr/resolve_variant_unittest.cc

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/developer/debug/zxdb/expr/resolve_variant.h"

#include <gtest/gtest.h>

#include "src/developer/debug/zxdb/expr/expr_value.h"
#include "src/developer/debug/zxdb/expr/mock_eval_context.h"
#include "src/developer/debug/zxdb/symbols/base_type.h"
#include "src/developer/debug/zxdb/symbols/collection.h"
#include "src/developer/debug/zxdb/symbols/data_member.h"
#include "src/developer/debug/zxdb/symbols/type_test_support.h"
#include "src/developer/debug/zxdb/symbols/variant.h"
#include "src/developer/debug/zxdb/symbols/variant_part.h"

namespace zxdb {

// Tests a variant with two possible values represented by discriminants 0 and
// 1.
TEST(ResolveVariant, TwoValues) {
  auto eval_context = fxl::MakeRefCounted<MockEvalContext>();

  // Random collection to serve as the enclosing struct.
  auto coll = fxl::MakeRefCounted<Collection>(DwarfTag::kStructureType, "Foo");

  auto a = fxl::MakeRefCounted<Variant>(0, std::vector<LazySymbol>{});
  auto b = fxl::MakeRefCounted<Variant>(1, std::vector<LazySymbol>{});

  // 8-bit discriminant.
  auto u8_type = fxl::MakeRefCounted<BaseType>(BaseType::kBaseTypeUnsigned, 1, "u8");
  auto discr = fxl::MakeRefCounted<DataMember>(std::string(), u8_type, 0);

  auto rust_enum = MakeRustEnum("RustEnum", discr, {a, b});
  auto variant_part = rust_enum->variant_part().Get()->AsVariantPart();

  // A value.
  ExprValue a_value(rust_enum, {0});
  fxl::RefPtr<Variant> output;
  Err err = ResolveVariant(eval_context, a_value, coll.get(), variant_part, &output);
  EXPECT_FALSE(err.has_error());
  EXPECT_EQ(a.get(), output.get());

  // B value.
  ExprValue b_value(rust_enum, {1});
  err = ResolveVariant(eval_context, b_value, coll.get(), variant_part, &output);
  EXPECT_FALSE(err.has_error());
  EXPECT_EQ(b.get(), output.get());

  // Invalid value.
  ExprValue invalid_value(rust_enum, {2});
  err = ResolveVariant(eval_context, invalid_value, coll.get(), variant_part, &output);
  EXPECT_TRUE(err.has_error());
  EXPECT_EQ(err.msg(), "Discriminant value of 0x2 does not match any of the Variants.");
}

TEST(ResolveVariant, DefaultValue) {
  auto eval_context = fxl::MakeRefCounted<MockEvalContext>();

  // Random collection to serve as the enclosing struct.
  auto coll = fxl::MakeRefCounted<Collection>(DwarfTag::kStructureType, "Foo");

  // Here b has no discriminant value, making it the default.
  auto a = fxl::MakeRefCounted<Variant>(0, std::vector<LazySymbol>{});
  auto b = fxl::MakeRefCounted<Variant>(std::nullopt, std::vector<LazySymbol>{});

  // 8-bit discriminant.
  auto u8_type = fxl::MakeRefCounted<BaseType>(BaseType::kBaseTypeUnsigned, 1, "u8");
  auto discr = fxl::MakeRefCounted<DataMember>(std::string(), u8_type, 0);

  auto rust_enum = MakeRustEnum("RustEnum", discr, {a, b});
  auto variant_part = rust_enum->variant_part().Get()->AsVariantPart();

  // A value.
  ExprValue a_value(rust_enum, {0});
  fxl::RefPtr<Variant> output;
  Err err = ResolveVariant(eval_context, a_value, coll.get(), variant_part, &output);
  EXPECT_FALSE(err.has_error());
  EXPECT_EQ(a.get(), output.get());

  // Any other value should give B.
  ExprValue b_value(rust_enum, {99});
  err = ResolveVariant(eval_context, b_value, coll.get(), variant_part, &output);
  EXPECT_FALSE(err.has_error());
  EXPECT_EQ(b.get(), output.get());
}

}  // namespace zxdb