Log Check Tests

worldCreateSaveTest loads your mod on a game test server, creates and saves a world, and then checks that every log line you listed in build.gradle.kts appeared. No window opens.

build.gradle.kts

tasks.named<dev.polymodloader.devtools.gradle.minecraft.VerifiedGameRunTask>("worldCreateSaveTest") {
    expectedOutput.add("[ruby_mod] Hello from ruby_mod 0.1.0")
}

Windows (PowerShell)

.\gradlew.bat worldCreateSaveTest

macOS · Linux (bash)

./gradlew worldCreateSaveTest

• Use it to check the "execution path", for example whether the entrypoint ran and whether the server started.
• Write the log lines from your mod code with SLF4J.

static final Logger LOGGER = LoggerFactory.getLogger("ruby_mod");

LOGGER.info("[ruby_mod] Hello from {} {}", mod.modId(), mod.modVersion());

Log lines and files to check

worldCreateSaveTest, gameTests, and serverBootSmokeTest are the same task type (VerifiedGameRunTask). Two properties list what to check.

Property	Meaning
expectedOutput	Strings that must appear in the game output. A partial match of a line is enough
expectedFiles	Files and folders that must exist after the game ends. Paths are relative to the run directory

build.gradle.kts

tasks.named<dev.polymodloader.devtools.gradle.minecraft.VerifiedGameRunTask>("worldCreateSaveTest") {
    expectedOutput.add("[ruby_mod] Hello from ruby_mod 0.1.0")
    expectedFiles.add(".poly/startup-report.json")
}

• add adds to the items the task already checks. set replaces the original items.
• The world of worldCreateSaveTest is saved in universe/gametestworld/ in the run directory.
• Poly Mod Loader reports appear in .poly/ in the run directory (Troubleshooting).

What the tasks check by default

The mod plugin adds these items when it creates the tasks. The items you write are added to them.

Task	Default log line	Default file
worldCreateSaveTest	All 1 required tests passed	universe/gametestworld/level.dat
gameTests	required tests passed	None
serverBootSmokeTest	None	None
clientWorldReloadTest	joined the game	—

A check task works like this.

1. It deletes the run directory (build/poly/…) and starts in an empty directory.
2. It shows the game output in the console and collects it.
3. When the game ends, it writes the whole output to verified-run-output.log in the run directory.
4. If even one log line (missing log line: …) or file (missing file: …) is missing, the task fails. The error message shows the path of the output log.
5. If everything is there, it prints … passed (N log lines, M files verified).

Client check

clientWorldReloadTest is a different task type (ClientWorldReloadTask). It copies the world that worldCreateSaveTest saved into the client's saves/ and opens it right away. The client cannot run without a window, so a window opens briefly.

build.gradle.kts

tasks.named<dev.polymodloader.devtools.gradle.minecraft.ClientWorldReloadTask>("clientWorldReloadTest") {
    // The common entrypoint also runs on the client.
    expectedOutput.add("[ruby_mod] Hello from ruby_mod 0.1.0")
}

Property	Meaning
expectedOutput	Strings that must appear in the client output
timeoutSeconds	Maximum time to wait (180 seconds by default)
systemProperties	Java system properties to pass to the client (key=value)

• When every expected line has appeared, it closes the client and passes.
• If the lines do not all appear in time, or the client ends first, it reports the missing lines and fails.
• The whole output is in client-world-reload-output.log in the run directory.

Use them together with in-game tests

Check game behavior with in-game tests, and check flows such as load, start, and save with log check tests.