Notation in npm solidity-coverage tests

Question

I had been using the npm package solidity-coverage and while reading the coverage reports I came up with this E symbol. I am not sure what it means and there is no explanation in the documentation as well. Does anyone know what this means?

Answer 1

A require(cond, msg) statement is technically a "shortcut" for:

if (cond)
    /* do some stuff */;
else
    revert(msg);

Hence an E in the solidity-coverage report means that although the if case has been covered, the else case has not been covered.

In your specific case, the function has been executed only with to != address(0).

In order to cover the other case, you'll need to execute it with to = address(0), for example:

try {
    await func("0x0");
    throw null;
}
catch (error) {
    assert(error, "Expected an error but did not get one");
    assert(error.message.startsWith("revert"), "Expected an error starting with 'revert' but got '" + error.message + "' instead");
}