subcommand method ParameterException is hidden by InvocationTargetException

[SysLord]

picocli/src/main/java/picocli/CommandLine.java

Line 1072 in 9d086d9

executionResult.add(((Method) command).invoke(parsed.getCommandSpec().parent().userObject(), parsed.getCommandSpec().argValues()));

Actual behaviour: Throwing a ParameterException from a command method is wrapped in InvocationTargetException and is not catched and handled as ParameterException. No help output.
Expected behaviour: ParameterExceptions get handled like in Callable or Runnable methods and print help.

[remkop]

Can you please provide a way to reproduce the problem? Ideally some source code for the command and user input that triggers the problem.

[remkop]

I was able to reproduce the issue with the following test:

class Test538 {
    @Rule
    public final SystemErrRule systemErrRule = new SystemErrRule().enableLog().muteForSuccessfulTests();

    @Rule
    public final SystemOutRule systemOutRule = new SystemOutRule().enableLog().muteForSuccessfulTests();

    /** Test for https://github.com/remkop/picocli/issues/554 */
    @Command(name = "maincommand")
    class MainCommand implements Runnable {
        @Spec CommandSpec spec;

        public void run() { throw new UnsupportedOperationException("must specify a subcommand"); }

        @Command
        public void subcommand(@Option(names = "-x") String x) {
            System.out.println("x=" + x);
        }

        @Command
        public void explicit(@Option(names = "-v") boolean v) {
            CommandLine commandLine = spec.subcommands().get("explicit");
            throw new CommandLine.ParameterException(commandLine, "Validation failed");
        }
    }

    @Test
    public void testSubcommandMethodExceptionHandling() {
        String expected = String.format("" +
                "Unknown option: -y%n" +
                "Usage: maincommand subcommand [-x=<arg0>]%n" +
                "  -x=<arg0>%n");

        CommandLine.run(new MainCommand(), "subcommand", "-y");
        assertEquals(expected, this.systemErrRule.getLog());
        assertEquals("", this.systemOutRule.getLog());
    }

    @Test
    public void testSubcommandMethodThrowingParameterException() {
        String expected = String.format("" +
                "Validation failed%n" +
                "Usage: maincommand explicit [-v]%n" +
                "  -v%n");

        CommandLine.run(new MainCommand(), "explicit", "-v");
        assertEquals(expected, this.systemErrRule.getLog());
        assertEquals("", this.systemOutRule.getLog());
    }
}

Note to self: the patch below fixes the problem.

Index: src/main/java/picocli/CommandLine.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/main/java/picocli/CommandLine.java	(revision )
+++ src/main/java/picocli/CommandLine.java	(revision )
@@ -1081,12 +1081,17 @@
                     }
                     throw new UnsupportedOperationException("Invoking non-static method without default constructor not implemented");
                 }
-            } catch (ParameterException ex) {
-                throw ex;
-            } catch (ExecutionException ex) {
-                throw ex;
+            } catch (InvocationTargetException ex) {
+                Throwable t = ex.getTargetException();
+                if (t instanceof ParameterException) {
+                    throw (ParameterException) t;
+                } else if (t instanceof ExecutionException) {
+                    throw (ExecutionException) t;
+                } else {
+                    throw new ExecutionException(parsed, "Error while calling command (" + command + "): " + t, t);
+                }
             } catch (Exception ex) {
-                throw new ExecutionException(parsed, "Error while calling command (" + command + "): " + ex, ex);
+                throw new ExecutionException(parsed, "Unhandled error while calling command (" + command + "): " + ex, ex);
             }
         }
         throw new ExecutionException(parsed, "Parsed command (" + command + ") is not Method, Runnable or Callable");
@@ -9926,8 +9931,8 @@
             super(msg);
             this.commandLine = Assert.notNull(commandLine, "commandLine");
         }
-        public ExecutionException(CommandLine commandLine, String msg, Exception ex) {
-            super(msg, ex);
+        public ExecutionException(CommandLine commandLine, String msg, Throwable t) {
+            super(msg, t);
             this.commandLine = Assert.notNull(commandLine, "commandLine");
         }
         /** Returns the {@code CommandLine} object for the (sub)command that could not be invoked.

I will apply this fix as soon as I can.

[SysLord]

Exactly. Thank you for looking into this. I just went looking into providing the required information, but you were faster.

[remkop]

Fixed in master.