Hide some test helper functions

Summary: [Folly] Hide some test helper functions to permit some tests to be linked together into the same binary, if desired.

Differential Revision: D18746529

fbshipit-source-id: 9829eb1227cb348f65734ceb670c85508577763d

folly/experimental/coro/test/AccumulateTest.cpp

@@ -25,6 +25,8 @@
 
 using namespace folly::coro;
 
+namespace {
+
 AsyncGenerator<int> generateInts(int begin, int end) {
   for (int i = begin; i < end; i++) {
     co_await co_reschedule_on_current_executor;
@@ -32,6 +34,8 @@ AsyncGenerator<int> generateInts(int begin, int end) {
   }
 }
 
+} // namespace
+
 TEST(AccumulateTest, NoOperationProvided) {
   auto result = blockingWait(accumulate(generateInts(0, 5), 0));
   auto expected = 0 + 1 + 2 + 3 + 4;

folly/experimental/coro/test/ConcatTest.cpp

@@ -27,6 +27,8 @@
 using namespace ::testing;
 using namespace folly::coro;
 
+namespace {
+
 AsyncGenerator<int> generateInts(int begin, int end) {
   for (int i = begin; i < end; i++) {
     co_await co_reschedule_on_current_executor;
@@ -42,6 +44,8 @@ Task<std::vector<int>> toVector(AsyncGenerator<int> generator) {
   co_return result;
 }
 
+} // namespace
+
 TEST(ConcatTest, ConcatSingle) {
   auto gen = concat(generateInts(0, 5));
   auto result = blockingWait(toVector(std::move(gen)));