Truffle cannot find Ethereum client when running tests

Question

By default this is the content of the file truffle.js:

module.exports = {
    // See <http://truffleframework.com/docs/advanced/configuration>
    // to customize your Truffle configuration!
};

When I execute the command truffle test with the above configuration, it work well. However, if I change the configuration to this:

module.exports = {
    networks: {
        test: {
            network_id: '*',
            gas: 4712388,
            gasPrice: 10
        }
    }
};

When I execute the command truffle test I get the following error:

Could not connect to your Ethereum client. Please check that your Ethereum client:
    - is running
    - is accepting RPC connections (i.e., "--rpc" option is used in geth)
    - is accessible over the network
    - is properly configured in your Truffle configuration file (truffle.js)

I tried setting options host and port but still not working.

I'm using Truffle v4.1.14 on Mac.

Answer 1

For those who may stumble across this: I was stuck on this recently - everything seemed to be set correctly but Truffle refused to connect to Ganache (or vice versa). I kept getting the "Could not connect to your Ethereum client" message. On a lark, I tried changing the host address in truffle.js to reflect the computer's actual internal IP address (e.g. 10.10.1.188), and then telling Ganache to run on the Ethernet address instead of loopback. Much to my surprise, it worked immediately. I haven't yet figured out why (firewall rule? codebase issue?).

I realize this is not a best practice because your internal IP will change. But if you're in need of a temporary workaround, this may help.

Answer 2

It sounds like when you change the configuration of the test network, Truffle Develop is not initialized automatically. So in order to make this work I had to run Truffle Develop manually:

truffle develop

And then in the truffle.js I put this config:

module.exports = {
    networks: {
        test: {
            network_id: '*',
            host: '127.0.0.1',
            port: 9545,
            gas: 6712388,
            gasPrice: 100000000000
        }
    }
};

Doing that it started to work. I guess if you specify any of the parameters in the test network you have to manually take care of having the Ethereum client running.

Answer 3

Beware that default network is development-

If you define test network, then you need to use parameter --network test

Code from truffle truffle test

// if "development" exists, default to using that for testing
if (!config.network && config.networks.development) {
  config.network = "development";
}

if (!config.network) {
  config.network = "test";
}