Fix for regression in open_succeeds_twice and `minimal_writer_examp…

…le` tests (#1667)

* Use test-specific temp subfolder to avoid leftovers from previous run

Signed-off-by: Michael Orlov <michael.orlov@apex.ai>

* Address flakiness in TestRosbag2CPPAPI::minimal_writer_example

- The `serialized_msg2` is not owning the serialized data after the
first call writer.write(serialized_msg2,..). i.e. need to use another
message or another API in test for second call to writer.write(msg).

Signed-off-by: Michael Orlov <michael.orlov@apex.ai>

---------

Signed-off-by: Michael Orlov <michael.orlov@apex.ai>

rosbag2_compression/test/rosbag2_compression/test_sequential_compression_writer.cpp

@@ -214,7 +214,7 @@ TEST_F(SequentialCompressionWriterTest, open_succeeds_on_supported_compression_f
     kDefaultCompressionQueueThreadsPriority};
   initializeWriter(compression_options);
 
-  auto tmp_dir = fs::temp_directory_path() / "path_not_empty";
+  auto tmp_dir = tmp_dir_ / "path_not_empty";
   auto storage_options = rosbag2_storage::StorageOptions();
   storage_options.uri = tmp_dir.string();
 
@@ -230,8 +230,8 @@ TEST_F(SequentialCompressionWriterTest, open_succeeds_twice)
     kDefaultCompressionQueueThreadsPriority};
   initializeWriter(compression_options);
 
-  auto tmp_dir = fs::temp_directory_path() / "path_not_empty";
-  auto tmp_dir_next = fs::temp_directory_path() / "path_not_empty_next";
+  auto tmp_dir = tmp_dir_ / "path_not_empty";
+  auto tmp_dir_next = tmp_dir_ / "path_not_empty_next";
 
   auto storage_options = rosbag2_storage::StorageOptions();
   auto storage_options_next = rosbag2_storage::StorageOptions();

rosbag2_tests/test/rosbag2_tests/test_rosbag2_cpp_api.cpp

@@ -108,9 +108,7 @@ TEST_P(TestRosbag2CPPAPI, minimal_writer_example)
     writer.open(rosbag_directory_next.string());
 
     // write same topic to different bag
-    writer.write(
-      serialized_msg2, "/yet/another/topic", "test_msgs/msg/BasicTypes",
-      rclcpp::Clock().now());
+    writer.write(bag_message, "/my/other/topic", "test_msgs/msg/BasicTypes");
 
     // close by scope
   }
@@ -154,7 +152,7 @@ TEST_P(TestRosbag2CPPAPI, minimal_writer_example)
       &extracted_serialized_msg, &extracted_test_msg);
 
     EXPECT_EQ(test_msg, extracted_test_msg);
-    EXPECT_EQ("/yet/another/topic", topic);
+    EXPECT_EQ("/my/other/topic", topic);
   }
 
   // alternative reader