package: require plugins to be non-empty

.github/workflows/build.yml

@@ -28,7 +28,7 @@ jobs:
         path: |
           ~/.gradle/caches/
           ~/.gradle/wrapper/
-        key: package-2.0.4
+        key: package-2.0.5
     - name: prepare
       run: |
         pushd package
@@ -80,7 +80,7 @@ jobs:
         path: |
           ~/.gradle/caches/
           ~/.gradle/wrapper/
-        key: upload-2.0.4
+        key: upload-2.0.5
     - uses: actions/download-artifact@v2
       with:
         name: manifest_diff

package/package/src/main/java/net/runelite/pluginhub/packager/Plugin.java

@@ -627,6 +627,21 @@ public class Plugin implements Closeable
 					.trimResults()
 					.splitToList(pluginsStr);
 
+				if (plugins.isEmpty())
+				{
+					throw PluginBuildException.of(this, "No plugin classes listed")
+						.withHelp(() ->
+						{
+							String m = "You must list your plugin class names in the plugin descriptor";
+							if (!pluginClasses.isEmpty())
+							{
+								m += "\nPerhaps you wanted plugins=" + String.join(", ", pluginClasses);
+							}
+							return m;
+						})
+						.withFileLine(propFile, "plugins=" + pluginsStr);
+				}
+
 				manifest.setPlugins(plugins.toArray(new String[0]));
 
 				for (String className : plugins)

package/package/src/test/java/net/runelite/pluginhub/packager/PluginTest.java

@@ -100,6 +100,26 @@ public class PluginTest
 		}
 	}
 
+	@Test
+	public void testEmptyPlugins() throws DisabledPluginException, PluginBuildException, IOException, InterruptedException
+	{
+		try (Plugin p = createExamplePlugin("empty-plugins"))
+		{
+			File propFile = new File(p.repositoryDirectory, "runelite-plugin.properties");
+			Properties props = Plugin.loadProperties(propFile);
+			props.setProperty("plugins", "");
+			writeProperties(props, propFile);
+			p.build(Util.readRLVersion());
+			p.assembleManifest();
+			Assert.fail();
+		}
+		catch (PluginBuildException e)
+		{
+			log.info("ok: ", e);
+			assertContains(e.getHelpText(), "com.example.ExamplePlugin");
+		}
+	}
+
 	@Test
 	public void testUnverifiedDependency() throws InterruptedException, DisabledPluginException, PluginBuildException, IOException
 	{