cpp-lazy-stream/test/stream_fluent_test.cxx

//
//  stream_fluent.t.h
//  stream
//
//  Created by Sam Jaffe on 1/28/17.
//

#include "xcode_gtest_helper.h"

#include <vector>

#include "stream/streams.hpp"
#include "stream/streams/fluent.hpp"

using ::testing::ElementsAreArray;
using ::testing::Eq;

TEST(FluentStreamTest, CollectToObjectPreservesElements) {
  std::vector<int> input{1, 2, 3, 4, 5};
  auto s = stream::of(input);
  std::set<int> out{};

  EXPECT_THAT(s > out, ElementsAreArray(input));
}

TEST(FluentStreamTest, MapToSelfIsSelfs) {
  std::vector<int> input{1, 2, 3, 4, 5};
  auto identity = [](int i) { return i; };
  auto s = stream::of(input) | identity;

  EXPECT_THAT(s.collect(), Eq(input));
}

TEST(FluentStreamTest, MapCanAlterValues) {
  std::vector<int> input{1, 2, 3, 4, 5};
  std::vector<int> expected{3, 5, 7, 9, 11};
  auto fmap = [](int i) { return 2 * i + 1; };
  auto s = stream::of(input) | fmap;

  EXPECT_THAT(s.collect(), Eq(expected));
}

TEST(FluentStreamTest, CanMapElementToBool) {
  std::vector<int> input{1, 2, 3, 4, 5};
  std::vector<bool> expected{false, true, false, true, false};
  auto even = [](int i) { return i % 2 == 0; };
  auto s = stream::of(input) | even;

  EXPECT_THAT(s.collect(), Eq(expected));
}

TEST(FluentStreamTest, CanFilterOutElements) {
  std::vector<int> input{1, 2, 3, 4, 5};
  std::vector<int> expected{2, 4};
  auto even = [](int i) { return i % 2 == 0; };
  auto s = stream::of(input) % even;

  EXPECT_THAT(s.collect(), Eq(expected));
}

TEST(FluentStreamTest, NoOpFilterReturnOriginal) {
  std::vector<int> input{1, 2, 3, 4, 5};
  auto pass = [](int) { return true; };
  auto s = stream::of(input) % pass;

  EXPECT_THAT(s.collect(), Eq(input));
}

TEST(FluentStreamTest, AccumulateDefaultsToAdd) {
  std::vector<int> input{1, 2, 3, 4, 5};
  auto even = [](int i) { return i % 2 == 0; };
  auto sum = [](int lhs, int rhs) { return lhs + rhs; };
  auto s = stream::of(input) % even;
  EXPECT_THAT(s > sum, Eq(6));
}

TEST(FluentStreamTest, FlatmapJoinsIterableOutputs) {
  std::vector<int> vv{1, 2, 3, 4, 5};
  auto next3 = [](int i) { return std::vector<int>{i, i + 1, i + 2}; };
  std::vector<int> expected{1, 2, 3, 2, 3, 4, 3, 4, 5, 4, 5, 6, 5, 6, 7};
  auto s = stream::of(vv) || next3;

  EXPECT_THAT(s.collect(), Eq(expected));
}