Occasionally, CVL lacks a feature that is necessary for a complete verification of a contract. We are working to extend the feature set of CVL to cover these cases, but in the mean time we have developed a set of workarounds that we refer to as “harnesses”.


Consider a scenario where we want to write a unit test for an internal functions of a contract. The contract serves as a workaround, allowing us to call original functions rather than relying on summarized implementations.

contract ExampleHarnessing is ExampleHarnessingGetter {
    constructor(Configuration memory config) ExampleHarnessingGetter(config) { }
    // External wrapper for accrueInternal
    function call_accrueInternal() external {
        return super.accrueInternal();

    // External wrapper for getNowInternal
    function call_getNowInternal() external view returns (uint40) {
        return super.getNowInternal();

    // Compute the n-th power of 10
    function powerOfTen(uint8 n) public pure returns (uint64){
        return uint64(uint64(10) ** n);

for more details checkout the source code

Here’s a brief overview:

unit test internal functions

call_accrueInternal and call_getNowInternal: External wrappers facilitating access to internal functions like accrueInternal and getNowInternal.

define complex functionally (view/pure)

powerOfTen: A utility function to compute the n-th power of 10.