# Java test coverage

> Set up Supercov with your agent, or run it yourself with Maven or Gradle.

Web page: https://supercov.com/docs/java
All Supercov pages for agents: https://supercov.com/llms.txt · Full text: https://supercov.com/llms-full.txt

Ask your coding agent to set up Supercov in your project:

```text supercov-prompt
Install Supercov with brew install supercorp-ai/tap/supercov, or take the
platform archive from the GitHub release. Read supercov docs and check the
supported JDK before running our existing Maven or Gradle tests. Show the
coverage report and any measurement limits. Don't change application code or
tests.
```

## Run it yourself

Java support requires a JDK 17 or newer with Maven or Gradle. Java and Kotlin
have no package registry of their own here, so a JVM project takes the binary
directly:

```sh
brew install supercorp-ai/tap/supercov
supercov --version
```

`npx supercov` works where Node.js is already present, and the platform
archives on the [latest release](https://github.com/supercorp-ai/supercov/releases/latest)
carry the same build at the same version.

### Run your tests

From your project root:

```sh
supercov -- mvn test
supercov -- ./gradlew test
```

Keep the flags your build normally uses. Supercov drives Maven and Gradle as
your test command rather than as a plugin: it adds the JUnit Platform launcher
it needs to the build file inside its own isolated workspace copy, so your
`pom.xml` and `build.gradle` are never edited.

Supercov measures every JUnit Platform engine — JUnit 5, JUnit 4 through
Vintage, Kotest and Spock — as well as TestNG.

Inspect the run:

```sh
supercov runs latest
supercov runs latest gaps --limit 5
```

## Check what the tests assert

Line coverage tells you a statement ran. It does not tell you that a test
checked the result. Supercov can ask [Jev](https://typesafe.ai) whether each test would fail if a
statement it ran changed. `runs latest assertions assess` saves the answers
(it needs `TYPESAFE_API_KEY`), and `runs latest assertions` then lists the
statements no test checks, file by file. A statement that is not asserted
runs in some test, but nothing that test checks depends on it. See
[Assertion coverage](https://supercov.com/docs/assertions?language=java).

## JVM-specific limits

Supercov measures the classes your build compiles for the test run. Generated
sources are measured only when the build includes them. See
[runner support](https://supercov.com/docs/supported-suites?language=java#java-and-kotlin) for the detail
available from each engine and its measurement limits.

Already using JaCoCo or OpenClover? See [how the reports differ](https://supercov.com/compare/java-code-coverage.md).
`supercov docs coverage-model` prints the guide for your installed version.