Implement support for commands as things.

With CommandThing and its parser, it is now possible to use commands anywhere a thing can be used. Commands are invoked as the console/server, and they support a single variable, the name of the recipient player.

Commands are give-only, meaning they will fail to be "taken" from players, and they cannot be "held" either. The idea of commands as things basically only makes sense in the context of rewards.

src/test/java/com/garbagemule/MobArena/things/CommandThingParserTest.java

@@ -0,0 +1,91 @@
+package com.garbagemule.MobArena.things;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.nullValue;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class CommandThingParserTest {
+
+    private CommandThingParser subject;
+
+    @Rule
+    public ExpectedException exception = ExpectedException.none();
+
+    @Before
+    public void setup() {
+        subject = new CommandThingParser();
+    }
+
+    @Test
+    public void emptyStringReturnsNull() {
+        Thing result = subject.parse("");
+
+        assertThat(result, is(nullValue()));
+    }
+
+    @Test
+    public void commandWithoutPrefixReturnsNull() {
+        Thing result = subject.parse("/give <player> dirt");
+
+        assertThat(result, is(nullValue()));
+    }
+
+    @Test
+    public void barePrefixReturnsNull() {
+        Thing result = subject.parse("cmd");
+
+        assertThat(result, is(nullValue()));
+    }
+
+    @Test
+    public void commandWithShortPrefix() {
+        String command = "/give <player> dirt";
+
+        Thing result = subject.parse("cmd:" + command);
+
+        Thing expected = new CommandThing(command);
+        assertThat(result, equalTo(expected));
+    }
+
+    @Test
+    public void commandWithLongPrefix() {
+        String command = "/give <player> dirt";
+
+        Thing result = subject.parse("command:" + command);
+
+        Thing expected = new CommandThing(command);
+        assertThat(result, equalTo(expected));
+    }
+
+    @Test
+    public void commandWithTitle() {
+        String command = "/give <player> dirt";
+        String title = "the best command";
+
+        Thing result = subject.parse("cmd(" + title + "):" + command);
+
+        Thing expected = new CommandThing(command, title);
+        assertThat(result, equalTo(expected));
+    }
+
+    @Test
+    public void missingCloseParenThrows() {
+        exception.expect(IllegalArgumentException.class);
+
+        subject.parse("cmd(name:/give <player> dirt");
+    }
+
+    @Test
+    public void missingColonAfterTitleThrows() {
+        exception.expect(IllegalArgumentException.class);
+
+        subject.parse("cmd(name)");
+    }
+
+}