[Issue_515] Provide a CliMain variant that doesn't call System.exit

prospero-cli/src/main/java/org/wildfly/prospero/cli/CliMain.java

@@ -49,17 +49,14 @@ private static void enableJBossLogManager() {
         }
     }
 
-    private static final Logger logger = Logger.getLogger(CliMain.class);
+    static final Logger logger = Logger.getLogger(CliMain.class);
 
     public static void main(String[] args) {
         try {
-            CliConsole console = new CliConsole();
-            CommandLine commandLine = createCommandLine(console, args);
-            int exitCode = commandLine.execute(args);
+            int exitCode = execute(args);
             System.exit(exitCode);
         } catch (Exception e) {
-            System.err.println(CliMessages.MESSAGES.errorWhenProcessingCommand() + e.getMessage());
-            logger.error(CliMessages.MESSAGES.errorWhenProcessingCommand(), e);
+            logException(e);
             System.exit(ReturnCodes.PROCESSING_ERROR);
         }
     }
@@ -111,4 +108,15 @@ public static CommandLine createCommandLine(CliConsole console, String[] args, A
         return commandLine;
     }
 
+    static int execute(String[] args) {
+        CliConsole console = new CliConsole();
+        CommandLine commandLine = createCommandLine(console, args);
+        return commandLine.execute(args);
+    }
+
+    static void logException(Exception e) {
+        System.err.println(CliMessages.MESSAGES.errorWhenProcessingCommand() + e.getMessage());
+        logger.error(CliMessages.MESSAGES.errorWhenProcessingCommand(), e);
+    }
+
 }

prospero-cli/src/main/java/org/wildfly/prospero/cli/CliMainNoExit.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2023 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.wildfly.prospero.cli;
+
+import static org.wildfly.prospero.cli.CliMain.execute;
+import static org.wildfly.prospero.cli.CliMain.logException;
+
+/**
+ * Variant of {@link CliMain} that doesn't call {@link System#exit(int)}.
+ * Meant for embedded use cases, for example Maven build executions.
+ */
+public class CliMainNoExit {
+
+    public static void main(String[] args) {
+        try {
+            int exitCode = execute(args);
+            if (exitCode != 0) {
+                System.err.println(CliMessages.MESSAGES.unexpectedExitWhenProcessingCommand(exitCode));
+                CliMain.logger.error(CliMessages.MESSAGES.unexpectedExitWhenProcessingCommand(exitCode));
+            }
+        } catch (Exception e) {
+            logException(e);
+        }
+    }
+}

prospero-cli/src/main/java/org/wildfly/prospero/cli/CliMessages.java

@@ -184,6 +184,10 @@ default String errorWhenProcessingCommand() {
         return bundle.getString("prospero.general.processing_error") + " ";
     }
 
+    default String unexpectedExitWhenProcessingCommand(int exitCode) {
+        return format(bundle.getString("prospero.general.processing_exit error"), exitCode);
+    }
+
     default String possibleDowngrade() {
         return bundle.getString("prospero.updates.downgrade.warning");
     }

prospero-cli/src/main/resources/UsageMessages.properties

@@ -312,6 +312,7 @@ prospero.general.prompt.reminder=Choose [y/N]:
 prospero.general.prompt.yes=y
 prospero.general.prompt.no=n
 prospero.general.processing_error=Error when processing command:
+prospero.general.processing_exit_error=Error when processing command: Exit code %.2f"
 prospero.general.operation.completed.time=Operation completed in %.2f seconds.
 prospero.general.error.header=ERROR: %s
 prospero.general.error.ssl=SSL error, maybe you forgot to configure the certificates