Web3j-unit is a Junit 5 extension to streamline the creation of Ethereum contract tests.

Multiple Ethereum implementations are supported including Geth and Besu. To run tests built using Web3j-unit, docker is required on the host.

Instances of Web3j, TransactionManager and GasProvider are injected into the Junit runner.

You can find a sample here.

You can find an example using docker-compose here. This spins up VMWare Concord nodes using a docker-compose file.

1. Add dependency to gradle.

   repositories {
      mavenCentral()
      maven { url "https://hyperledger.jfrog.io/artifactory/besu-maven/" }
      maven { url "https://artifacts.consensys.net/public/maven/maven/" }
      maven { url "https://splunk.jfrog.io/splunk/ext-releases-local" }
      maven { url "https://dl.cloudsmith.io/public/consensys/quorum-mainnet-launcher/maven/" }
   }

   implementation "org.web3j:core:4.14.0"
   testCompile "org.web3j:web3j-unit:4.14.0"

2. Create a new test with the @EVMTest annotation. An embedded EVM is used by default. To use Geth or Besu pass the node type into the annotation: @EVMTest(NodeType.GETH) or @EVMTest(NodeType.BESU)

@EVMTest
class GreeterTest {

}

3. Inject instance of Web3j TransactionManager and ContractGasProvider in your test method.

@EVMTest
class GreeterTest {

    @Test
    fun greeterDeploys(
        web3j: Web3j,
        transactionManager: TransactionManager,
        gasProvider: ContractGasProvider
    ) {}

}

4. Deploy your contract in the test.

@EVMTest
class GreeterTest {

    @Test
    fun greeterDeploys(
        web3j: Web3j,
        transactionManager: TransactionManager,
        gasProvider: ContractGasProvider
    ) {
        val greeter = Greeter.deploy(web3j, transactionManager, gasProvider, "Hello EVM").send()
        val greeting = greeter.greet().send()
        assertEquals("Hello EVM", greeting)
    }

}

5. Run the test!

1. Add dependency to gradle.

  repositories {
     mavenCentral()
  }

  implementation "org.web3j:core:4.14.0"
  testCompile "org.web3j:web3j-unit:4.14.0"

2. Create a new test with the @EVMComposeTest annotation. By default, uses test.yml file in the project home, and runs web3j on service name node1 exposing the port 8545. Can be customised to use specific docker-compose file, service name and port by @EVMComposeTest("src/test/resources/geth.yml", "ethnode1", 8080) Here, we connect to the service named ethnode1 in the src/test/resources/geth.yml docker-compose file which exposes the port 8080 for web3j to connect to.

@EVMComposeTest("src/test/resources/geth.yml", "ethnode1", 8080)
class GreeterTest {

}

3. Inject instance of Web3j TransactionManager and ContractGasProvider in your test method.

@EVMComposeTest("src/test/resources/geth.yml", "ethnode1", 8080)
class GreeterTest {

    @Test
    fun greeterDeploys(
        web3j: Web3j,
        transactionManager: TransactionManager,
        gasProvider: ContractGasProvider
    ) {}

}

4. Deploy your contract in the test.

@EVMComposeTest("src/test/resources/geth.yml", "ethnode1", 8080)
class GreeterTest {

    @Test
    fun greeterDeploys(
        web3j: Web3j,
        transactionManager: TransactionManager,
        gasProvider: ContractGasProvider
    ) {
        val greeter = Greeter.deploy(web3j, transactionManager, gasProvider, "Hello EVM").send()
        val greeting = greeter.greet().send()
        assertEquals("Hello EVM", greeting)
    }

}

5. Run the test!