cpp-shared-random-generator/test/tape_test.cxx

//
//  tape_test.cpp
//  shared_random_generator-test
//
//  Created by Sam Jaffe on 3/19/23.
//  Copyright © 2023 Sam Jaffe. All rights reserved.
//

#include "random/tape.h"

#include <cstdlib>

#include <scope_guard/scope_guard.hpp>

#include "random/distribution.h"
#include "random/random.h"

#include "xcode_gtest_helper.h"

using testing::ElementsAre;
using testing::FieldsAre;

template <typename T> class Uniform : public engine::random::Uniform<T> {
public:
  Uniform(T min, T max) : engine::random::Uniform<T>(min, max) {}

  T operator()(engine::random::Device &) const final { throw; }
};

MATCHER_P(BytesAre, value, "") {
  *result_listener << "whose bytes are " << std::hex << arg;
  return reinterpret_cast<double const &>(arg) == value;
}

TEST(TapeTest, CanRecordIntData) {
  engine::random::Tape tape;

  tape.apply(Uniform(0u, 100u), 50u);
  EXPECT_EQ(tape.apply(Uniform(0u, 100u)), 50);
}

TEST(TapeTest, CanRecordDoubleData) {
  engine::random::Tape tape;

  tape.apply(Uniform(0.0, 100.0), 50.0);
  EXPECT_EQ(tape.apply(Uniform(0.0, 100.0)), 50.0);

  tape.apply(Uniform(0.0, 100.0), 50.0);
  EXPECT_EQ(tape.apply(Uniform(0.0, 100.0)), 50.0);
}

TEST(TapeTest, ThrowsOnOverFetch) {
  engine::random::Tape tape;
  tape.apply(Uniform(0, 100), 50);
  EXPECT_EQ(tape.apply(Uniform(0, 100)), 50);
  EXPECT_THROW(tape.apply(Uniform(0, 100)), std::out_of_range);
}

TEST(TapeTest, BadRequestIsNoOp) {
  engine::random::Tape tape;
  tape.apply(Uniform(0, 100), 50);
  EXPECT_ANY_THROW(tape.apply(Uniform(0, 1)));
  EXPECT_EQ(tape.apply(Uniform(0, 100)), 50);
}

TEST(TapeTest, ThrowsOnTypeMismatch) {
  engine::random::Tape tape;
  tape.apply(Uniform(0u, 100u), 50u);
  EXPECT_THROW(tape.apply(Uniform(0.0, 100.0)), std::logic_error);
  EXPECT_THROW(tape.apply(Uniform(0, 100)), std::logic_error);
  EXPECT_NO_THROW(tape.apply(Uniform(0u, 100u)));
}

TEST(TapeTest, ThrowsOnBoundsMismatch) {
  engine::random::Tape tape;
  tape.apply(Uniform(0.0, 100.0), 50.0);
  EXPECT_THROW(tape.apply(Uniform(0.0, 1.0)), std::logic_error);
}

TEST(TapeTest, IsOrdered) {
  engine::random::Tape tape;
  tape.apply(Uniform(0.0, 100.0), 50.0);
  tape.apply(Uniform(10.0, 90.0), 50.0);

  EXPECT_THROW(tape.apply(Uniform(10.0, 90.0)), std::logic_error);

  EXPECT_EQ(tape.apply(Uniform(0.0, 100.0)), 50.0);
  EXPECT_EQ(tape.apply(Uniform(10.0, 90.0)), 50.0);
}

TEST(TapeTest, IsSerializable) {
  engine::random::Tape tape;
  tape.apply(Uniform(0, 100), 50);
  tape.apply(Uniform(0u, 100u), 50u);
  tape.apply(Uniform(0.0, 100.0), 50.0);

  auto serial = engine::random::Tape::serial_type(tape);
  EXPECT_THAT(serial, ElementsAre(FieldsAre("iUniform[0,100]", 50),
                                  FieldsAre("jUniform[0,100]", 50),
                                  FieldsAre("dUniform[0,100)", BytesAre(50))));

  tape = engine::random::Tape(serial);
  EXPECT_EQ(tape.apply(Uniform(0, 100)), 50);
  EXPECT_EQ(tape.apply(Uniform(0u, 100u)), 50u);
  EXPECT_EQ(tape.apply(Uniform(0.0, 100.0)), 50.0);
}

TEST(TapeTest, IndexNotIncludedInSerialization) {
  engine::random::Tape tape;
  tape.apply(Uniform(0, 100), 50);
  tape.apply(Uniform(0u, 100u), 50u);
  tape.apply(Uniform(0.0, 100.0), 50.0);

  EXPECT_EQ(tape.apply(Uniform(0, 100)), 50);
  EXPECT_EQ(tape.apply(Uniform(0u, 100u)), 50u);

  auto serial = engine::random::Tape::serial_type(tape);
  EXPECT_THAT(serial, ElementsAre(FieldsAre("iUniform[0,100]", 50),
                                  FieldsAre("jUniform[0,100]", 50),
                                  FieldsAre("dUniform[0,100)", BytesAre(50))));

  tape = engine::random::Tape(serial);
  EXPECT_EQ(tape.apply(Uniform(0, 100)), 50);
  EXPECT_EQ(tape.apply(Uniform(0u, 100u)), 50u);
  EXPECT_EQ(tape.apply(Uniform(0.0, 100.0)), 50.0);
}

TEST(TapeTest, CanAttachToRandom) {
  engine::random::Random random;
  auto tape = std::make_shared<engine::random::Tape>();

  auto scope = random.record(tape);

  auto result = random(engine::random::Uniform(0, 100));
  EXPECT_EQ(tape->apply(engine::random::Uniform(0, 100)), result);
}

TEST(TapeTest, StopsRecordingOnScopeExit) {
  engine::random::Random random;
  auto tape = std::make_shared<engine::random::Tape>();

  {
    auto scope = random.record(tape);
    random(engine::random::Uniform(0, 100));
  }
  random(engine::random::Uniform(0, 100));

  EXPECT_NO_THROW(tape->apply(engine::random::Uniform(0, 100)));
  EXPECT_THROW(tape->apply(engine::random::Uniform(0, 100)), std::out_of_range);
}