Add experimental client game test

build.gradle

@@ -20,6 +20,16 @@ chenille {
     javaVersion = 17
 }
 
+loom {
+    runs {
+        clientGametest {
+            inherit testmodClient
+            name "Client Game Test"
+            vmArg "-Dfabric.client.gametest"
+        }
+    }
+}
+
 repositories {
     chenille.repositories {
         ladysnake()

src/testmod/java/org/ladysnake/impersonatest/ImpersonateClientTestSuite.java

@@ -0,0 +1,68 @@
+package org.ladysnake.impersonatest;
+
+import net.fabricmc.fabric.api.client.gametest.v1.ClientGameTestContext;
+import net.fabricmc.fabric.api.client.gametest.v1.FabricClientGameTest;
+import net.fabricmc.loader.api.FabricLoader;
+import net.minecraft.SharedConstants;
+import net.minecraft.client.gui.screen.GameMenuScreen;
+import net.minecraft.client.gui.screen.TitleScreen;
+import net.minecraft.client.gui.screen.world.CreateWorldScreen;
+import net.minecraft.client.gui.screen.world.LevelLoadingScreen;
+import net.minecraft.client.gui.screen.world.SelectWorldScreen;
+import net.minecraft.client.option.Perspective;
+import net.minecraft.client.util.InputUtil;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.DirectoryStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+public class ImpersonateClientTestSuite implements FabricClientGameTest {
+    @Override
+    public void runTest(ClientGameTestContext context) {
+        context.waitForScreen(TitleScreen.class);
+        context.clickScreenButton("menu.singleplayer");
+
+        if (!isDirEmpty(FabricLoader.getInstance().getGameDir().resolve("saves"))) {
+            context.waitForScreen(SelectWorldScreen.class);
+            context.clickScreenButton("selectWorld.create");
+        }
+
+        context.waitForScreen(CreateWorldScreen.class);
+        context.runOnClient(client -> CreateWorldScreen.showTestWorld(client, client.currentScreen));
+        context.waitForScreen(CreateWorldScreen.class);
+        context.clickScreenButton("selectWorld.create");
+
+        context.waitFor(client -> client.player != null && !(client.currentScreen instanceof LevelLoadingScreen), 30 * SharedConstants.TICKS_PER_MINUTE);
+        context.waitTicks(20); // a few more ticks for world loading
+
+        context.runOnClient(client -> client.options.setPerspective(Perspective.THIRD_PERSON_FRONT));
+        sendChatMessage(context, "before_impersonation");
+        context.runOnClient(client -> client.getNetworkHandler().sendChatCommand("impersonate disguise as Pyrofab"));
+        context.waitTicks(20);
+        sendChatMessage(context, "impersonating_pyrofab");
+        context.runOnClient(client -> client.getNetworkHandler().sendChatCommand("impersonate disguise as doctor4t"));
+        context.waitTicks(20);
+        sendChatMessage(context, "impersonating_doctor4t");
+
+        context.setScreen(() -> new GameMenuScreen(true));
+        context.clickScreenButton("menu.returnToMenu");
+    }
+
+    private static void sendChatMessage(ClientGameTestContext context, String screenshotName) {
+        context.getInput().pressKey(options -> options.chatKey);
+        context.waitTick();
+        context.getInput().typeChars("Hello, World!");
+        context.getInput().pressKey(InputUtil.GLFW_KEY_ENTER);
+        context.takeScreenshot(screenshotName, 5);
+    }
+
+    private static boolean isDirEmpty(Path path) {
+        try (DirectoryStream<Path> directory = Files.newDirectoryStream(path)) {
+            return !directory.iterator().hasNext();
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+}

src/testmod/resources/fabric.mod.json

@@ -23,6 +23,9 @@
     ],
     "fabric-gametest": [
       "org.ladysnake.impersonatest.ImpersonateTestSuite"
+    ],
+    "fabric-client-gametest": [
+      "org.ladysnake.impersonatest.ImpersonateClientTestSuite"
     ]
   },
   "depends": {