Allow CommandMetadata to be injected into Cli commands

src/main/java/io/airlift/airline/Cli.java

@@ -123,7 +123,7 @@ public C parse(Iterable<String> args)
                 command.getArguments(),
                 state.getParsedArguments(),
                 command.getMetadataInjections(),
-                ImmutableMap.<Class<?>, Object>of(GlobalMetadata.class, metadata));
+                ImmutableMap.<Class<?>, Object>of(GlobalMetadata.class, metadata, CommandMetadata.class, command));
     }
 
     private void validate(ParseState state)

src/test/java/io/airlift/airline/CommandTest.java

@@ -33,6 +33,7 @@
 import io.airlift.airline.args.ArgsRequired;
 import io.airlift.airline.args.ArgsSingleChar;
 import io.airlift.airline.args.Arity1;
+import io.airlift.airline.args.CommandWithHelp;
 import io.airlift.airline.args.OptionsRequired;
 import io.airlift.airline.command.CommandAdd;
 import io.airlift.airline.command.CommandCommit;
@@ -382,4 +383,10 @@ class A
         }
         singleCommandParser(A.class).parse("-lon", "32");
     }
+
+	public void helpOption()
+	{
+		CommandWithHelp command = singleCommandParser(CommandWithHelp.class).parse("CommandWithHelp", "-h");
+		Assert.assertTrue(command.helpOption.showHelpIfRequested());
+	}
 }

src/test/java/io/airlift/airline/args/CommandWithHelp.java

@@ -0,0 +1,31 @@
+/**
+ * Copyright (C) 2010 the original author or authors.
+ * See the notice.md file distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * 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 io.airlift.airline.args;
+
+import io.airlift.airline.Command;
+import io.airlift.airline.HelpOption;
+
+import javax.inject.Inject;
+
+@Command(name = "CommandWithHelp")
+public class CommandWithHelp
+{
+	@Inject
+	public HelpOption helpOption;
+}