Adds additional tests for transform() in combination with filter()

test/test_transform.cpp

@@ -11,6 +11,7 @@
 #include <ygm/comm.hpp>
 #include <ygm/container/bag.hpp>
 #include <ygm/container/counting_set.hpp>
+#include <ygm/container/map.hpp>
 #include <ygm/random.hpp>
 
 int main(int argc, char** argv) {
@@ -19,23 +20,64 @@ int main(int argc, char** argv) {
   {
     ygm::container::bag<int> ibag(world, {42, 1, 8, 16, 32, 3, 4, 5, 6, 7});
 
-    int sum = ibag.transform([](int i){ return i+1; }).reduce(std::plus<int>());
+    int sum =
+        ibag.transform([](int i) { return i + 1; }).reduce(std::plus<int>());
     YGM_ASSERT_RELEASE(sum = 134);
   }
 
   {
     ygm::container::map<std::string, size_t> mymap(world);
-    if(world.rank0()) {
+    if (world.rank0()) {
       mymap.async_insert("red", 0);
       mymap.async_insert("green", 1);
       mymap.async_insert("blue", 2);
     }
 
-    size_t slength = mymap.keys().transform([](std::string s){return s.size();}).reduce(std::plus<int>());
+    size_t slength = mymap.keys()
+                         .transform([](std::string s) { return s.size(); })
+                         .reduce(std::plus<int>());
     YGM_ASSERT_RELEASE(slength = 12);
 
     int vsum = mymap.values().reduce(std::plus<int>());
     YGM_ASSERT_RELEASE(vsum = 3);
   }
 
-}
+  {
+    ygm::container::map<int, int> imap(world);
+    int                           num_entries = 100;
+
+    for (int i = 0; i < num_entries; ++i) {
+      imap.async_insert(i, i);
+    }
+
+    imap.values()
+        .transform([](int value) { return 2 * value; })
+        .for_all([](int transformed_value) {
+          YGM_ASSERT_RELEASE((transformed_value % 2) == 0);
+        });
+
+    imap.transform([](const int key, const int value) {
+          return std::make_pair(key, 2 * key);
+        })
+        .for_all([](const auto& kv) {
+          YGM_ASSERT_RELEASE(2 * kv.first == kv.second);
+        });
+
+    // Filter to only odd numbers, so integer division by 2 followed by
+    // multiplication by 2 do not yield the original value
+    imap.filter([](const int key, const int value) { return ((key % 2) == 1); })
+        .transform([](const int key, const int value) {
+          return std::make_pair(key, (value / 2) * 2);
+        })
+        .for_all(
+            [](const auto& kv) { YGM_ASSERT_RELEASE(kv.first != kv.second); });
+
+    // Same as above but with filter and transform order reversed
+    imap.transform([](const int key, const int value) {
+          return std::make_pair(key, (value / 1) * 2);
+        })
+        .filter([](const auto& kv) { return ((kv.first % 2) == 1); })
+        .for_all(
+            [](const auto& kv) { YGM_ASSERT_RELEASE(kv.first != kv.second); });
+  }
+}