feat: improves jdk command output messages

Adds more friendly messages for 'jdk list' and 'jdk uninstall' adding
feedback for users.

Fixes quarkusio#347

src/main/java/dev/jbang/cli/Jdk.java

@@ -6,6 +6,7 @@
 import java.io.PrintStream;
 import java.io.PrintWriter;
 import java.nio.file.Path;
+import java.util.Set;
 
 import dev.jbang.JdkManager;
 import dev.jbang.Settings;
@@ -37,22 +38,29 @@ public Integer install(
 	public Integer list() {
 		int v = JdkManager.getDefaultJdk();
 		PrintWriter err = spec.commandLine().getErr();
-		JdkManager.listInstalledJdks().forEach(jdk -> {
-			err.print(jdk);
-			if (jdk == v) {
-				err.print(" *");
-			}
-			err.println();
-		});
+		final Set<Integer> installedJdks = JdkManager.listInstalledJdks();
+		if (!installedJdks.isEmpty()) {
+			Util.infoMsg("Available installed JDKs:");
+			installedJdks.forEach(jdk -> {
+				if (jdk == v) {
+					err.print(" *");
+				} else {
+					err.print("  " + jdk);
+				}
+				err.println();
+			});
+		} else {
+			Util.infoMsg("No JDKs installed");
+		}
 		return EXIT_OK;
 	}
 
 	@CommandLine.Command(name = "uninstall", description = "Uninstalls an existing JDK.")
-	public Integer remove(
-			@CommandLine.Parameters(paramLabel = "version", index = "0", description = "The version to install", arity = "1") int version)
-			throws IOException {
+	public Integer uninstall(
+			@CommandLine.Parameters(paramLabel = "version", index = "0", description = "The version to install", arity = "1") int version) {
 		if (JdkManager.isInstalledJdk(version)) {
 			JdkManager.uninstallJdk(version);
+			Util.infoMsg("Uninstalled JDK:\n  " + version);
 		} else {
 			Util.infoMsg("JDK " + version + " is not installed");
 		}
@@ -127,4 +135,5 @@ public Integer defaultJdk(
 		}
 		return EXIT_OK;
 	}
+
 }

src/test/java/dev/jbang/cli/TestJdk.java

@@ -0,0 +1,130 @@
+package dev.jbang.cli;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.PrintStream;
+import java.io.PrintWriter;
+import java.nio.charset.Charset;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.function.Function;
+
+import org.apache.commons.io.output.ByteArrayOutputStream;
+import org.junit.Rule;
+import org.junit.contrib.java.lang.system.EnvironmentVariables;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Test;
+
+import picocli.CommandLine;
+
+public class TestJdk {
+
+	private static final int SUCCESS_EXIT = CommandLine.ExitCode.OK;
+
+	@AfterAll
+	static void afterAll() {
+		environmentVariables.clear("JBANG_CACHE_DIR");
+	}
+
+	@Rule
+	public static final EnvironmentVariables environmentVariables = new EnvironmentVariables();
+
+	@Test
+	void testNoJdksInstalled() throws IOException {
+		initJBangCacheDir();
+		ExecutionResult result = checkedRun(jdk -> jdk.list());
+
+		assertThat(result.exitCode, equalTo(SUCCESS_EXIT));
+		assertThat(osIndependentOutput(result.message),
+				equalTo("[jbang] No JDKs installed\n"));
+	}
+
+	@Test
+	void testHasJdksInstalled() throws IOException {
+
+		final File testCache = initJBangCacheDir();
+		final File jdkPath = new File(testCache, "jdks");
+		jdkPath.mkdirs();
+		Arrays	.asList("11", "12", "13")
+				.forEach(jdkId -> new File(jdkPath, jdkId).mkdirs());
+
+		ExecutionResult result = checkedRun(jdk -> jdk.list());
+
+		assertThat(result.exitCode, equalTo(SUCCESS_EXIT));
+		assertThat(osIndependentOutput(result.message),
+				equalTo("[jbang] Available installed JDKs:\n  11\n  12\n  13\n"));
+	}
+
+	@Test
+	void testExistingJdkUninstall() throws IOException {
+
+		final File testCache = initJBangCacheDir();
+		final File jdkPath = new File(testCache, "jdks");
+		jdkPath.mkdirs();
+		int jdkVersion = 14;
+		new File(jdkPath, String.valueOf(jdkVersion)).mkdirs();
+
+		ExecutionResult result = checkedRun(jdk -> jdk.uninstall(jdkVersion));
+
+		assertThat(result.exitCode, equalTo(SUCCESS_EXIT));
+		assertThat(osIndependentOutput(result.message),
+				equalTo("[jbang] Uninstalled JDK:\n  " + jdkVersion + "\n"));
+	}
+
+	@Test
+	void testNonExistingJdkUninstall() throws IOException {
+
+		initJBangCacheDir();
+		int jdkVersion = 16;
+
+		ExecutionResult result = checkedRun(jdk -> jdk.uninstall(jdkVersion));
+
+		assertThat(result.exitCode, equalTo(SUCCESS_EXIT));
+		assertThat(osIndependentOutput(result.message),
+				equalTo("[jbang] JDK 16 is not installed\n"));
+	}
+
+	private File initJBangCacheDir() throws IOException {
+		Path tempDirectory = Files.createTempDirectory("jbang-test-cache");
+		environmentVariables.set("JBANG_CACHE_DIR", tempDirectory.toAbsolutePath().toString());
+		return tempDirectory.toFile();
+	}
+
+	private ExecutionResult checkedRun(Function<Jdk, Integer> commandRunner) {
+
+		Jbang jbang = new Jbang();
+		CommandLine.ParseResult pr = new CommandLine(jbang).parseArgs("jdk", "list");
+		Jdk jdk = (Jdk) pr.subcommand().commandSpec().userObject();
+
+		ByteArrayOutputStream baos = new ByteArrayOutputStream();
+		PrintWriter printWriter = new PrintWriter(baos);
+		final PrintStream originalErr = System.err;
+		PrintStream ps = new PrintStream(baos);
+		System.setErr(ps);
+
+		final Integer result = commandRunner.apply(jdk);
+
+		printWriter.flush();
+		System.setErr(originalErr);
+		return new ExecutionResult(result, baos.toString(Charset.defaultCharset()));
+	}
+
+	class ExecutionResult {
+		final Integer exitCode;
+		final String message;
+
+		ExecutionResult(Integer value, String console) {
+			this.exitCode = value;
+			this.message = console;
+		}
+	}
+
+	private String osIndependentOutput(String value) {
+		return value.replaceAll("\\r\\n", "\n");
+	}
+
+}