Added an additional test for --help in neo4j-admin

and made code slightly more robust to avoid nullpointerexceptions

community/command-line/src/main/java/org/neo4j/commandline/admin/AdminTool.java

@@ -105,6 +105,12 @@ public void execute( Path homeDir, Path configDir, String... args )
                 return;
             }
 
+            if ( provider == null )
+            {
+                badUsage( format( "unrecognized command: %s", name ) );
+                return;
+            }
+
             if ( Args.parse( commandArgs ).has( "help" ) )
             {
                 outsideWorld.stdErrLine( "unknown argument: --help" );

community/command-line/src/test/java/org/neo4j/commandline/admin/AdminToolTest.java

@@ -245,7 +245,22 @@ public void shouldNotBlockIfNoneOfTheBlockersBlock() throws CommandFailed, Incor
     }
 
     @Test
-    public void helpArgumentShouldAlwaysPrintHelp() throws CommandFailed, IncorrectUsage
+    public void helpArgumentPrintsHelp() throws CommandFailed, IncorrectUsage
+    {
+        AdminCommand command = mock( AdminCommand.class );
+        OutsideWorld outsideWorld = mock( OutsideWorld.class );
+
+        new AdminTool( cannedCommand( "command", command ), new NullBlockerLocator(), outsideWorld, false )
+                .execute( null, null, "--help" );
+
+        verifyNoMoreInteractions( command );
+        verify( outsideWorld ).stdErrLine( "unrecognized command: --help" );
+        verify( outsideWorld ).stdErrLine( "usage: neo4j-admin <command>" );
+        verify( outsideWorld ).exit( STATUS_ERROR );
+    }
+
+    @Test
+    public void helpArgumentPrintsHelpForCommand() throws CommandFailed, IncorrectUsage
     {
         AdminCommand command = mock( AdminCommand.class );
         OutsideWorld outsideWorld = mock( OutsideWorld.class );