Test suite fixes (#124)

* Move polling strategy adapter definition into test_utils.cpp

* Use a random consumer group id in every test

tests/test_utils.cpp

@@ -0,0 +1,94 @@
+#include <cstdint>
+#include <iomanip>
+#include <limits>
+#include <sstream>
+#include <random>
+#include "test_utils.h"
+
+using std::chrono::duration_cast;
+using std::chrono::milliseconds;
+using std::chrono::seconds;
+using std::chrono::system_clock;
+using std::hex;
+using std::move;
+using std::numeric_limits;
+using std::ostringstream;
+using std::random_device;
+using std::string;
+using std::uniform_int_distribution;
+using std::unique_ptr;
+using std::vector;
+
+//==================================================================================
+//                           PollStrategyAdapter
+//==================================================================================
+
+PollStrategyAdapter::PollStrategyAdapter(Configuration config)
+ : Consumer(config) {
+}
+
+void PollStrategyAdapter::add_polling_strategy(unique_ptr<PollInterface> poll_strategy) {
+    strategy_ = move(poll_strategy);
+}
+
+void PollStrategyAdapter::delete_polling_strategy() {
+    strategy_.reset();
+}
+
+Message PollStrategyAdapter::poll() {
+    if (strategy_) {
+        return strategy_->poll();
+    }
+    return Consumer::poll();
+}
+
+Message PollStrategyAdapter::poll(milliseconds timeout) {
+    if (strategy_) {
+        return strategy_->poll(timeout);
+    }
+    return Consumer::poll(timeout);
+}
+
+vector<Message> PollStrategyAdapter::poll_batch(size_t max_batch_size) {
+    if (strategy_) {
+        return strategy_->poll_batch(max_batch_size);
+    }
+    return Consumer::poll_batch(max_batch_size);
+}
+
+vector<Message> PollStrategyAdapter::poll_batch(size_t max_batch_size, milliseconds timeout) {
+    if (strategy_) {
+        return strategy_->poll_batch(max_batch_size, timeout);
+    }
+    return Consumer::poll_batch(max_batch_size, timeout);
+}
+
+void PollStrategyAdapter::set_timeout(milliseconds timeout) {
+    if (strategy_) {
+        strategy_->set_timeout(timeout);
+    }
+    else {
+        Consumer::set_timeout(timeout);
+    }
+}
+
+milliseconds PollStrategyAdapter::get_timeout() {
+    if (strategy_) {
+        return strategy_->get_timeout();
+    }
+    return Consumer::get_timeout();
+}
+
+// Misc
+
+string make_consumer_group_id() {
+    ostringstream output;
+    output << hex;
+
+    random_device rd;
+    uniform_int_distribution<uint64_t> distribution(0, numeric_limits<uint64_t>::max());
+    const auto now = duration_cast<seconds>(system_clock::now().time_since_epoch());
+    const auto random_number = distribution(rd);
+    output << now.count() << random_number;
+    return output.str();
+}