Method operator -

tests/catch.hpp:12335–12341

namespace Catch {

    Counts Counts::operator - ( Counts const& other ) const {
        Counts diff;
        diff.passed = passed - other.passed;
        diff.failed = failed - other.failed;
        diff.failedButOk = failedButOk - other.failedButOk;
        return diff;
    }

    Counts& Counts::operator += ( Counts const& other ) {
        passed += other.passed;