cpp-lazy-stream/stream.t.h

//
//  stream_td.hpp
//  stream
//
//  Created by Sam Jaffe on 1/28/17.
//

#pragma once

#include <cxxtest/TestSuite.h>

#include <vector>

#include "streams.hpp"


class stream_TestSuite : public CxxTest::TestSuite {
public:
  using int_t = int const &;
  using vec_t = std::vector<int>;
public:
  void test_preserved() {
    vec_t v{1, 2, 3, 4, 5};
    auto s = stream::make_stream(v);
    vec_t o{s.begin(), s.end()};
    TS_ASSERT_EQUALS(v, o);
  }
  
  void test_collect_preserves() {
    vec_t v{1, 2, 3, 4, 5};
    auto s = stream::make_stream(v);
    vec_t o{s.begin(), s.end()};
    vec_t o2{s.collect()};
    TS_ASSERT_EQUALS(v, o);
    TS_ASSERT_EQUALS(v, o2);
  }

  void test_collect_arg_preserves() {
    vec_t v{1, 2, 3, 4, 5};
    auto s = stream::make_stream(v);
    std::set<int> o{};
    s.collect(o);
    for ( int i : v ) {
      TS_ASSERT_EQUALS(o.count( i ), 1);
    }
  }
  
  void test_map_identity() {
    vec_t v{1, 2, 3, 4, 5};
    auto identity = [](int_t i) { return i; };
    auto s = stream::make_stream(v).map( identity );
    vec_t o{s.begin(), s.end()};
    TS_ASSERT_EQUALS(v, o);
  }
  
  void test_map_change() {
    vec_t v{1, 2, 3, 4, 5};
    vec_t expected{3, 5, 7, 9, 11};
    auto fmap = [](int_t i) { return 2*i+1; };
    auto s = stream::make_stream(v).map( fmap );
    vec_t o{s.begin(), s.end()};
    TS_ASSERT_EQUALS(expected, o);
  }
  
  void test_filter_noop() {
    vec_t v{1, 2, 3, 4, 5};
    auto pass = [](int_t i) { return true; };
    auto s = stream::make_stream(v).filter( pass );
    vec_t o{s.begin(), s.end()};
    TS_ASSERT_EQUALS(v, o);
  }
  
  void test_filter_value() {
    vec_t v{1, 2, 3, 4, 5};
    vec_t expected{2, 4};
    auto even = [](int_t i) { return i%2 == 0; };
    auto s = stream::make_stream(v).filter( even );
    vec_t o{s.begin(), s.end()};
    TS_ASSERT_EQUALS(expected, o);
  }
  
  void test_accumulate() {
    vec_t 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).filter( even );
    TS_ASSERT_EQUALS( 6 , s.accumulate(sum, 0) );
  }
  
  void test_flatmap_joins_lists() {
    vec_t vv{1, 2, 3, 4, 5};
    auto next3 = [](int_t i) { return vec_t{i, i+1, i+2}; };
    vec_t expected{1, 2, 3, 2, 3, 4, 3, 4, 5, 4, 5, 6, 5, 6, 7};
    auto s = stream::make_stream(vv).flatmap( next3 );
    vec_t o{s.begin(), s.end()};
    TS_ASSERT_EQUALS(expected, o);
  }
  
  void test_dereference() {
    int val = 5;
    std::vector<int*> v{&val};
    auto data = stream::make_stream(v).deref().collect();
    TS_ASSERT_EQUALS(data.front(), val);
  }
};