cpp-json/test/json_binder_polymorphic_test.cxx

//
//  json_binder_polymorphic.t.h
//  json
//
//  Created by Sam Jaffe on 11/14/18.
//  Copyright © 2018 Sam Jaffe. All rights reserved.
//

#include "json/json_binder.hpp"
#include <gmock/gmock.h>

struct Base {
  virtual ~Base() = default;
  virtual void run() const = 0;
};

struct Left : public Base {
  int a;
  void run() const override {}
};

struct Right : public Base {
  std::string a;
  void run() const override {}
};

struct Middle : public Base {
  std::tuple<int, std::string> a;
  void run() const override {}
};

bool operator==(Left const & lhs, Left const & rhs) { return lhs.a == rhs.a; }

bool operator==(Right const & lhs, Right const & rhs) { return lhs.a == rhs.a; }

using namespace json::binder;
using namespace json::parser;

class JsonBinderPolymorphicTest : public ::testing::Test {
protected:
  using pBase = std::unique_ptr<Base>;

  polymorphic_binder<pBase> & GetBinder() {
    static polymorphic_binder<pBase> val = polymorphic_binder<pBase>()(
        "Left", object_binder<Left>()("a", &Left::a))(
        "Right", object_binder<Right>()("a", &Right::a));
    return val;
  }
};

template <typename T> bool instanceof (Base * ptr) {
  return dynamic_cast<T *>(ptr) != nullptr;
}

using namespace ::testing;

TEST_F(JsonBinderPolymorphicTest, CanHitLeftPolymorph) {
  char data[] = "{\"@id\":\"Left\", \"@value\":{\"a\":1}}";
  pBase out;
  Left expected;
  expected.a = 1;
  EXPECT_NO_THROW(parse(json::binder::bind(out, GetBinder()), data));
  EXPECT_THAT(out, Not(IsNull()));
  EXPECT_PRED1(instanceof <Left>, out.get());
  EXPECT_THAT(dynamic_cast<Left &>(*out), expected);
}

TEST_F(JsonBinderPolymorphicTest, CanHitRightPolymorph) {
  char data[] = "{\"@id\":\"Right\", \"@value\":{\"a\":\"hello\"}}";
  pBase out;
  Right expected;
  expected.a = "hello";
  EXPECT_NO_THROW(parse(json::binder::bind(out, GetBinder()), data));
  EXPECT_THAT(out, Not(IsNull()));
  EXPECT_PRED1(instanceof <Right>, out.get());
  EXPECT_THAT(dynamic_cast<Right &>(*out), expected);
}

TEST_F(JsonBinderPolymorphicTest, ThrowsOnUnknownSubclass) {
  char data[] = "{\"@id\":\"Middle\", \"@value\":{\"a\":[]]}}";
  pBase out;
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, ThrowsOnIdNotString) {
  char data[] = "{\"@id\":0, \"@value\":{\"a\":[]]}}";
  pBase out;
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, ThrowsOnUnexpectedKey1) {
  char data[] = "{\"@class\":\"Left\", \"@value\":{\"a\":[]]}}";
  pBase out;
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, ThrowsOnUnexpectedKey2) {
  char data[] = "{\"@id\":\"Left\", \"@impl\":null, \"@value\":{\"a\":[]]}}";
  pBase out;
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, ThrowsOnUnexpectedKey3) {
  char data[] = "{\"@id\":\"Left\", \"@impl\":{\"a\":[]]}}";
  pBase out;
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, ThrowsOnUnterminatedJson) {
  char data[] = "{\"@id\":\"Right\", \"@value\":{\"a\":\"hello\"}";
  pBase out;
  Right expected;
  expected.a = "hello";
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, Not(IsNull()));
  EXPECT_PRED1(instanceof <Right>, out.get());
  EXPECT_THAT(dynamic_cast<Right &>(*out), expected);
}

TEST_F(JsonBinderPolymorphicTest, ThrowsOnMoreData) {
  char data[] = "{\"@id\":\"Right\", \"@value\":{\"a\":\"hello\"},"
                " \"key\":null }";
  pBase out;
  Right expected;
  expected.a = "hello";
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, Not(IsNull()));
  EXPECT_PRED1(instanceof <Right>, out.get());
  EXPECT_THAT(dynamic_cast<Right &>(*out), expected);
}

TEST_F(JsonBinderPolymorphicTest, ThrowsOnNonObject) {
  char data[] = "[\"Right\", \"@value\":{\"a\":\"hello\"}]";
  pBase out;
  Right expected;
  expected.a = "hello";
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, ThrowsMalformedObjectKey) {
  char data[] = "{@id\":\"Right\", \"@value\":{\"a\":\"hello\"}}";
  pBase out;
  Right expected;
  expected.a = "hello";
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, ThrowsMalformedObjectAssoc) {
  char data[] = "{\"@id\"=\"Right\", \"@value\":{\"a\":\"hello\"}}";
  pBase out;
  Right expected;
  expected.a = "hello";
  EXPECT_THROW(parse(json::binder::bind(out, GetBinder()), data),
               json::malformed_json_exception);
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, WritesRightImplWithoutWhitespace) {
  std::string const expected = R"({"@id":"Right","@value":{"a":"hello"}})";
  Right in;
  in.a = "hello";
  pBase ptr(new Right(in));
  std::stringstream ss;
  EXPECT_NO_THROW(write(json::binder::bind(ptr, GetBinder()), ss));
  EXPECT_THAT(ss.str(), expected);
}

TEST_F(JsonBinderPolymorphicTest, WritesLeftImplWithoutWhitespace) {
  std::string const expected = R"({"@id":"Left","@value":{"a":1}})";
  Left in;
  in.a = 1;
  pBase ptr(new Left(in));
  std::stringstream ss;
  EXPECT_NO_THROW(write(json::binder::bind(ptr, GetBinder()), ss));
  EXPECT_THAT(ss.str(), expected);
}

TEST_F(JsonBinderPolymorphicTest, ThrowsWhenWritingUnboundImpl) {
  Middle in;
  in.a = {1, "hello"};
  pBase ptr(new Middle(in));
  std::stringstream ss;
  EXPECT_THROW(write(json::binder::bind(ptr, GetBinder()), ss),
               std::domain_error);
}

TEST_F(JsonBinderPolymorphicTest, ParsesNullSuccessfully) {
  char const data[] = "null";
  pBase out;
  EXPECT_NO_THROW(parse(json::binder::bind(out, GetBinder()), data));
  EXPECT_THAT(out, IsNull());
}

TEST_F(JsonBinderPolymorphicTest, WritesNullSuccessfully) {
  pBase ptr = nullptr;
  std::stringstream ss;
  EXPECT_NO_THROW(write(json::binder::bind(ptr, GetBinder()), ss));
  EXPECT_THAT(ss.str(), "null");
}