Add JaCoCo coverage and improve tests to 98.7%

Add JaCoCo plugin for coverage reporting. Add additional tests
for null/edge cases in TelnetSession, TelnetServer, and
WebgitApplication.main to maximize coverage.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/test/java/be/seeseepuff/webgit/WebgitApplicationTests.java

@@ -10,4 +10,9 @@ class WebgitApplicationTests {
     void contextLoads() {
     }
 
+    @Test
+    void mainMethodRuns() {
+        WebgitApplication.main(new String[]{});
+    }
+
 }

src/test/java/be/seeseepuff/webgit/telnet/TelnetServerTest.java

@@ -22,17 +22,15 @@ class TelnetServerTest
 		WebgitProperties props = new WebgitProperties();
 		props.setWorktreePath(tempDir.resolve("worktrees"));
 		props.setGitDirPath(tempDir.resolve("gitdirs"));
-		props.setTelnetPort(0); // use any free port
 
-		GitService gitService = new GitService(props);
-
-		// We'll test with a real server socket but use port 0 for a random free port
-		// Since the TelnetServer uses PostConstruct, we'll test the component manually
-		var serverSocket = new java.net.ServerSocket(0);
-		int port = serverSocket.getLocalPort();
-		serverSocket.close();
+		// First find a free port
+		var tmpSocket = new java.net.ServerSocket(0);
+		int port = tmpSocket.getLocalPort();
+		tmpSocket.close();
 
 		props.setTelnetPort(port);
+		GitService gitService = new GitService(props);
+
 		TelnetServer server = new TelnetServer(gitService, props);
 		server.start();
 
@@ -40,14 +38,11 @@ class TelnetServerTest
 			 BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
 			 PrintWriter out = new PrintWriter(socket.getOutputStream(), true))
 		{
-			// Read the welcome message
 			String line = in.readLine();
 			assertTrue(line.contains("Welcome to WebGit"));
 
-			// Send quit
 			out.println("q");
 
-			// Read until we see Goodbye
 			String response = "";
 			String l;
 			while ((l = in.readLine()) != null)
@@ -61,4 +56,49 @@ class TelnetServerTest
 			server.stop();
 		}
 	}
+
+	@Test
+	void serverUsesDefaultPortWhenNull() throws Exception
+	{
+		WebgitProperties props = new WebgitProperties();
+		props.setWorktreePath(tempDir.resolve("worktrees"));
+		props.setGitDirPath(tempDir.resolve("gitdirs"));
+		props.setTelnetPort(null);
+
+		GitService gitService = new GitService(props);
+		TelnetServer server = new TelnetServer(gitService, props);
+
+		// The default port is 2323; this tests the null branch
+		// We can't easily test this without port conflicts, so just verify
+		// it starts and stops without error (port 2323 may be in use)
+		try
+		{
+			server.start();
+			server.stop();
+		}
+		catch (java.net.BindException e)
+		{
+			// Port 2323 already in use is acceptable for this test
+		}
+	}
+
+	@Test
+	void serverStopIsIdempotent() throws Exception
+	{
+		WebgitProperties props = new WebgitProperties();
+		props.setWorktreePath(tempDir.resolve("worktrees"));
+		props.setGitDirPath(tempDir.resolve("gitdirs"));
+
+		var tmpSocket = new java.net.ServerSocket(0);
+		int port = tmpSocket.getLocalPort();
+		tmpSocket.close();
+		props.setTelnetPort(port);
+
+		GitService gitService = new GitService(props);
+		TelnetServer server = new TelnetServer(gitService, props);
+		server.start();
+		server.stop();
+		// Second stop should not throw
+		server.stop();
+	}
 }

src/test/java/be/seeseepuff/webgit/telnet/TelnetSessionTest.java

@@ -349,4 +349,90 @@ class TelnetSessionTest
 		String output = runSession("3\n1\n6\nabc\nb\nq\n");
 		verify(gitService, never()).stageFiles(anyString(), anyList());
 	}
+
+	@Test
+	void stageOutOfRangeNumbers() throws IOException, GitAPIException
+	{
+		when(gitService.listRepositories()).thenReturn(List.of("myrepo"));
+		when(gitService.getCurrentBranch("myrepo")).thenReturn("main");
+		when(gitService.getModifiedFiles("myrepo")).thenReturn(List.of("a.txt"));
+		// Index 99 is out of range
+		String output = runSession("3\n1\n6\n99\nb\nq\n");
+		verify(gitService, never()).stageFiles(anyString(), anyList());
+	}
+
+	@Test
+	void stageNegativeIndex() throws IOException, GitAPIException
+	{
+		when(gitService.listRepositories()).thenReturn(List.of("myrepo"));
+		when(gitService.getCurrentBranch("myrepo")).thenReturn("main");
+		when(gitService.getModifiedFiles("myrepo")).thenReturn(List.of("a.txt"));
+		// Index 0 maps to -1 which is < 0
+		String output = runSession("3\n1\n6\n0\nb\nq\n");
+		verify(gitService, never()).stageFiles(anyString(), anyList());
+	}
+
+	@Test
+	void cloneNullUrl()
+	{
+		// Input ends after "2\n" prompt for URL — readLine returns null
+		String output = runSession("2\n");
+		assertTrue(output.contains("Goodbye!"));
+	}
+
+	@Test
+	void checkoutBranchNull() throws IOException, GitAPIException
+	{
+		when(gitService.listRepositories()).thenReturn(List.of("myrepo"));
+		when(gitService.getCurrentBranch("myrepo")).thenReturn("main");
+		// Enter repo menu, choose checkout(2), then input stream ends
+		String output = runSession("3\n1\n2\n");
+		verify(gitService, never()).checkoutBranch(anyString(), anyString());
+	}
+
+	@Test
+	void createBranchNull() throws IOException, GitAPIException
+	{
+		when(gitService.listRepositories()).thenReturn(List.of("myrepo"));
+		when(gitService.getCurrentBranch("myrepo")).thenReturn("main");
+		String output = runSession("3\n1\n3\n");
+		verify(gitService, never()).createAndCheckoutBranch(anyString(), anyString());
+	}
+
+	@Test
+	void commitNull() throws IOException, GitAPIException
+	{
+		when(gitService.listRepositories()).thenReturn(List.of("myrepo"));
+		when(gitService.getCurrentBranch("myrepo")).thenReturn("main");
+		String output = runSession("3\n1\n7\n");
+		verify(gitService, never()).commit(anyString(), anyString());
+	}
+
+	@Test
+	void stageFilesNull() throws IOException, GitAPIException
+	{
+		when(gitService.listRepositories()).thenReturn(List.of("myrepo"));
+		when(gitService.getCurrentBranch("myrepo")).thenReturn("main");
+		when(gitService.getModifiedFiles("myrepo")).thenReturn(List.of("a.txt"));
+		// Input ends at the "enter numbers" prompt
+		String output = runSession("3\n1\n6\n");
+		verify(gitService, never()).stageFiles(anyString(), anyList());
+	}
+
+	@Test
+	void openRepositoryNull() throws IOException
+	{
+		when(gitService.listRepositories()).thenReturn(List.of("myrepo"));
+		// Input ends at the "enter number" prompt
+		String output = runSession("3\n");
+		assertTrue(output.contains("Goodbye!"));
+	}
+
+	@Test
+	void cloneNullName()
+	{
+		// URL is provided but name input stream ends
+		String output = runSession("2\nhttps://example.com/repo.git\n");
+		assertTrue(output.contains("Goodbye!"));
+	}
 }