Start SFTP server on an arbitrary free port.

This makes it possible to run multiple tests in parallel because they
don't use the same port anymore.

Author: stefanbirkner

README.md

@@ -12,7 +12,7 @@ Fake SFTP Server Rule is published under the
 if you want to use it with an older version of Java.
 
 I want to thank my former team SAM at ThoughtWorks for using this library and
-@crizzis and @OArtyomov for their feature requests.
+@crizzis, @OArtyomov and @TheSentinel454 for their feature requests.
 
 
 ## Installation
@@ -23,9 +23,11 @@ Fake SFTP Server Rule is available from
     <dependency>
       <groupId>com.github.stefanbirkner</groupId>
       <artifactId>fake-sftp-server-rule</artifactId>
-      <version>1.4.0</version>
+      <version>2.0.0</version>
     </dependency>
 
+If you upgrade from a version < 2.x to the newest version please read the last
+section of this readme.
 
 ## Usage
 
@@ -56,7 +58,8 @@ password, but you can restrict it to specific pairs.
 
 It is also possible to do this during the test using the same method.
 
-The port of the server is obtained by `sftpServer.getPort()`. You can change it
+By default the SFTP server listens on an auto-allocated port. During the test
+this port can be obtained by `sftpServer.getPort()`. It can be changed
 by calling `setPort(int)`. If you do this from within a test then the server
 gets restarted. The time-consuming restart can be avoided by setting the port
 immediately after creating the rule.
@@ -197,3 +200,15 @@ CI.
 * Commit the modified `pom.xml` and `README.md`.
 * Run `mvn clean deploy` with JDK 8.
 * Add a tag for the release: `git tag fake-sftp-server-rule-X.X.X`
+
+
+## Upgrading from 0.x.y or 1.x.y to version >= 2
+
+In older versions the SFTP server listened to port 23454 by default. From
+version 2 on it selects an arbitrary free port by default. If your tests fail
+after an upgrade you may consider to restore the old behaviour by immediately
+setting the old port after creating the rule.
+
+    @Rule
+    public final FakeSftpServerRule sftpServer = new FakeSftpServerRule()
+        .setPort(23454);

pom.xml

@@ -9,7 +9,7 @@
     </parent>
 
     <artifactId>fake-sftp-server-rule</artifactId>
-    <version>1.4.0</version>
+    <version>2.0.0</version>
     <packaging>jar</packaging>
 
     <name>Fake SFTP Server Rule</name>

src/main/java/com/github/stefanbirkner/fakesftpserver/rule/FakeSftpServerRule.java

@@ -51,11 +51,11 @@
  * }
  * </pre>
  * <p>It is also possible to do this during the test using the same method.
- * <p>The port of the server is obtained by
- * {@link #getPort() sftpServer.getPort()}. You can change it by calling
- * {@link #setPort(int)}. If you do this from within a test then the server gets
- * restarted. The time-consuming restart can be avoided by setting the port
- * immediately after creating the rule.
+ * <p>By default the SFTP server listens on an auto-allocated port. During the
+ * test this port can be obtained by {@link #getPort() sftpServer.getPort()}. It
+ * can be changed by calling {@link #setPort(int)}. If you do this from within a
+ * test then the server gets restarted. The time-consuming restart can be
+ * avoided by setting the port immediately after creating the rule.
  * <pre>
  * public class TestClass {
  *   &#064;Rule
@@ -178,18 +178,30 @@ public FileVisitResult postVisitDirectory(
             }
     };
     private final Map<String, String> usernamesAndPasswords = new HashMap<>();
-    private int port = 23454;
+    private int port = 0;
 
     private FileSystem fileSystem;
     private SshServer server;
 
     /**
-     * Returns the port of the SFTP server.
+     * Returns the port of the SFTP server. If the SFTP server listens on an
+     * auto-allocated port (that means you didn't call {@link #setPort(int)})
+     * then you can only call this method during the test.
      *
      * @return the port of the SFTP server.
+     * @throws IllegalStateException if you call the method outside of a test
+     * but haven't called {@link #setPort(int)}) before.
      */
     public int getPort() {
-        return port;
+        if (port == 0)
+            return getPortFromServer();
+        else
+            return port;
+    }
+
+    private int getPortFromServer() {
+        verifyThatTestIsRunning("call getPort()");
+        return server.getPort();
     }
 
     /**

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

@@ -782,24 +782,26 @@ public void existence_of_a_file_cannot_be_checked_after_the_test_is_finished() {
     public static class server_shutdown {
         @Test
         public void after_a_successful_test_SFTP_server_is_shutdown() {
-            FakeSftpServerRule sftpServer = new FakeSftpServerRule();
+            FakeSftpServerRule sftpServer = new FakeSftpServerRule()
+                .setPort(DUMMY_PORT);
             executeTestWithRule(
                 () -> {},
                 sftpServer
             );
-            assertConnectionToSftpServerNotPossible(sftpServer);
+            assertConnectionToSftpServerNotPossible(DUMMY_PORT);
         }
 
         @Test
         public void after_an_erroneous_test_SFTP_server_is_shutdown() {
-            FakeSftpServerRule sftpServer = new FakeSftpServerRule();
+            FakeSftpServerRule sftpServer = new FakeSftpServerRule()
+                .setPort(DUMMY_PORT);
             executeTestThatThrowsExceptionWithRule(
                 () -> {
                     throw new RuntimeException();
                 },
                 sftpServer
             );
-            assertConnectionToSftpServerNotPossible(sftpServer);
+            assertConnectionToSftpServerNotPossible(DUMMY_PORT);
         }
 
         @Test
@@ -823,12 +825,6 @@ public void after_a_test_second_SFTP_server_is_shutdown_when_port_was_changed_du
             assertConnectionToSftpServerNotPossible(DUMMY_PORT);
         }
 
-        private void assertConnectionToSftpServerNotPossible(
-            FakeSftpServerRule sftpServer
-        ) {
-            assertConnectionToSftpServerNotPossible(sftpServer.getPort());
-        }
-
         private void assertConnectionToSftpServerNotPossible(
             int port
         ) {
@@ -845,6 +841,26 @@ private void assertConnectionToSftpServerNotPossible(
     }
 
     public static class port_selection {
+        @Test
+        public void by_default_two_rules_run_servers_at_different_ports() {
+            FakeSftpServerRule firstSftpServer = new FakeSftpServerRule();
+            AtomicInteger portCaptureForFirstServer = new AtomicInteger();
+            FakeSftpServerRule secondSftpServer = new FakeSftpServerRule();
+            AtomicInteger portCaptureForSecondServer = new AtomicInteger();
+
+            executeTestWithRule(
+                () -> portCaptureForFirstServer.set(firstSftpServer.getPort()),
+                firstSftpServer
+            );
+            executeTestWithRule(
+                () -> portCaptureForSecondServer.set(secondSftpServer.getPort()),
+                secondSftpServer
+            );
+
+            assertThat(portCaptureForFirstServer)
+                .doesNotHaveValue(portCaptureForSecondServer.get());
+        }
+
         @Test
         public void the_port_can_be_changed_during_the_test() {
             FakeSftpServerRule sftpServer = new FakeSftpServerRule();
@@ -906,37 +922,79 @@ public void it_is_not_possible_to_set_a_port_greater_than_65535() {
         }
     }
 
+    @RunWith(Enclosed.class)
     public static class port_query {
-        @Test
-        public void port_can_be_read_before_the_test() {
-            FakeSftpServerRule sftpServer = new FakeSftpServerRule()
-                .setPort(DUMMY_PORT);
-            int port = sftpServer.getPort();
-            assertThat(port).isEqualTo(DUMMY_PORT);
-        }
 
-        @Test
-        public void port_can_be_read_during_the_test() {
-            AtomicInteger portCapture = new AtomicInteger();
-            FakeSftpServerRule sftpServer = new FakeSftpServerRule()
-                .setPort(DUMMY_PORT);
-            executeTestWithRule(
-                () -> portCapture.set(sftpServer.getPort()),
-                sftpServer
-            );
-            assertThat(portCapture).hasValue(DUMMY_PORT);
+        public static class random_port {
+            @Test
+            public void cannot_be_read_before_the_test() {
+                FakeSftpServerRule sftpServer = new FakeSftpServerRule();
+                assertPortCannotBeRead(sftpServer);
+            }
+
+            @Test
+            public void can_be_read_during_the_test() {
+                AtomicInteger portCapture = new AtomicInteger();
+                FakeSftpServerRule sftpServer = new FakeSftpServerRule();
+                executeTestWithRule(
+                    () -> portCapture.set(sftpServer.getPort()),
+                    sftpServer
+                );
+                assertThat(portCapture).doesNotHaveValue(0);
+            }
+
+            @Test
+            public void cannot_be_read_after_the_test() {
+                FakeSftpServerRule sftpServer = new FakeSftpServerRule();
+                executeTestWithRule(
+                    () -> {},
+                    sftpServer
+                );
+                assertPortCannotBeRead(sftpServer);
+            }
+
+            private void assertPortCannotBeRead(FakeSftpServerRule sftpServer) {
+                assertThatThrownBy(sftpServer::getPort)
+                    .isInstanceOf(IllegalStateException.class)
+                    .hasMessage(
+                        "Failed to call getPort() because test has not been"
+                            + " started or is already finished."
+                    );
+            }
         }
 
-        @Test
-        public void port_can_be_read_after_the_test() {
-            FakeSftpServerRule sftpServer = new FakeSftpServerRule()
-                .setPort(DUMMY_PORT);
-            executeTestWithRule(
-                () -> {},
-                sftpServer
-            );
-            int port = sftpServer.getPort();
-            assertThat(port).isEqualTo(DUMMY_PORT);
+        public static class specified_port {
+            @Test
+            public void can_be_read_before_the_test() {
+                FakeSftpServerRule sftpServer = new FakeSftpServerRule()
+                    .setPort(DUMMY_PORT);
+                int port = sftpServer.getPort();
+                assertThat(port).isEqualTo(DUMMY_PORT);
+            }
+
+            @Test
+            public void can_be_read_during_the_test() {
+                AtomicInteger portCapture = new AtomicInteger();
+                FakeSftpServerRule sftpServer = new FakeSftpServerRule()
+                    .setPort(DUMMY_PORT);
+                executeTestWithRule(
+                    () -> portCapture.set(sftpServer.getPort()),
+                    sftpServer
+                );
+                assertThat(portCapture).hasValue(DUMMY_PORT);
+            }
+
+            @Test
+            public void can_be_read_after_the_test() {
+                FakeSftpServerRule sftpServer = new FakeSftpServerRule()
+                    .setPort(DUMMY_PORT);
+                executeTestWithRule(
+                    () -> {},
+                    sftpServer
+                );
+                int port = sftpServer.getPort();
+                assertThat(port).isEqualTo(DUMMY_PORT);
+            }
         }
     }