cpp-lazy-stream/test/stream_fluent_test.cxx

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

#include <gmock/gmock.h>

#include <vector>

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

using ::testing::Eq;

using int_t = int const &;

TEST(FluentStreamTest, CollectToObjectPreservesElements) {
  std::vector<int> v{1, 2, 3, 4, 5};
  auto s = stream::make_stream(v);
  std::set<int> o{};
  s > o;
  for (int i : v ) {
    EXPECT_THAT(o.count(i), Eq(1));
  }
}

TEST(FluentStreamTest, MapToSelfIsSelfs) {
  std::vector<int> v{1, 2, 3, 4, 5};
  auto identity = [](int_t i) { return i; };
  auto s = stream::make_stream(v) | identity;
  std::vector<int> o{s.begin(), s.end()};
  EXPECT_THAT(o, Eq(v));
}

TEST(FluentStreamTest, MapCanAlterValues) {
  std::vector<int> v{1, 2, 3, 4, 5};
  std::vector<int> expected{3, 5, 7, 9, 11};
  auto fmap = [](int_t i) { return 2*i+1; };
  auto s = stream::make_stream(v) | fmap;
  std::vector<int> o{s.begin(), s.end()};
  EXPECT_THAT(o, Eq(expected));
}

TEST(FluentStreamTest, NoOpFilterReturnOriginal) {
  std::vector<int> v{1, 2, 3, 4, 5};
  auto pass = [](int_t) { return true; };
  auto s = stream::make_stream(v) | pass;
  std::vector<int> o{s.begin(), s.end()};
  EXPECT_THAT(o, Eq(v));
}

TEST(FluentStreamTest, CanFilterOutElements) {
  std::vector<int> v{1, 2, 3, 4, 5};
  std::vector<int> expected{2, 4};
  auto even = [](int_t i) { return i%2 == 0; };
  auto s = stream::make_stream(v) | even;
  std::vector<int> o{s.begin(), s.end()};
  EXPECT_THAT(o, Eq(expected));
}

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

TEST(FluentStreamTest, FlatmapJoinsIterableOutputs) {
  std::vector<int> vv{1, 2, 3, 4, 5};
  auto next3 = [](int_t 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::make_stream(vv) || next3;
  std::vector<int> o{s.begin(), s.end()};
  EXPECT_THAT(o, Eq(expected));
}