Extract assertEmptyDirectoryExists

This is a preparatory refactoring. The method will be used by another
test when we implement a `createDirectories` method.

Author: stefanbirkner

pom.xml

@@ -9,7 +9,7 @@
     </parent>
 
     <artifactId>fake-sftp-server-rule</artifactId>
-    <version>1.1.1</version>
+    <version>1.2.0-SNAPSHOT</version>
     <packaging>jar</packaging>
 
     <name>Fake SFTP Server Rule</name>

src/test/java/com/github/stefanbirkner/fakesftpserver/rule/FakeSftpServerRuleTest.java

@@ -312,12 +312,7 @@ public void a_directory_that_is_created_with_the_rule_can_be_read_by_a_client()
             executeTestWithRule(
                 () -> {
                     sftpServer.createDirectory("/a/directory");
-                    Session session = connectToServer(sftpServer);
-                    ChannelSftp channel = connectSftpChannel(session);
-                    Vector entries = channel.ls("/a/directory");
-                    assertThat(entries).hasSize(2); //these are the entries . and ..
-                    channel.disconnect();
-                    session.disconnect();
+                    assertEmptyDirectory(sftpServer, "/a/directory");
                 },
                 sftpServer
             );
@@ -354,6 +349,18 @@ public void a_directory_cannot_be_created_after_the_test_is_finished() {
                         + " started or is already finished."
                 );
         }
+
+        private static void assertEmptyDirectory(
+            FakeSftpServerRule sftpServer,
+            String directory
+        ) throws JSchException, SftpException {
+            Session session = connectToServer(sftpServer);
+            ChannelSftp channel = connectSftpChannel(session);
+            Vector entries = channel.ls(directory);
+            assertThat(entries).hasSize(2); //these are the entries . and ..
+            channel.disconnect();
+            session.disconnect();
+        }
     }
 
     @RunWith(Enclosed.class)