anchor.diff:  
     doCheck = false;
   
  +  doInstallCheck = true;
  +  installCheckPhase = ''
  +    runHook preInstallCheck
  +
  +    $out${passthru.shellPath} -c "
  +      fn expect {|key expected|
  +        var actual = \$buildinfo[\$key]
  +        if (not-eq \$actual \$expected) {
  +          fail '\$buildinfo['\$key']: expected '(to-string \$expected)', got '(to-string \$actual)
  +        }
  +      }
  +
  +      expect version ${version}
  +      expect reproducible \$true
  +    "
  +
  +    runHook postInstallCheck
  +  '';
  +
     meta = with lib; {
       description = "A friendly and expressive command shell";
       longDescription = ''
  
positive.code:     maintainers = with maintainers; [ vrthra AndersonTorres ];
    };
  
    passthru = {
      shellPath = "/bin/elvish";
      tests = runCommand "${pname}-buildinfo-test" {} ''
        mkdir $out
  
        ${elvish}/bin/elvish -c "
          fn expect {|key expected|
            var actual = \$buildinfo[\$key]
            if (not-eq \$actual \$expected) {
              fail '\$buildinfo['\$key']: expected '(to-string \$expected)', got '(to-string \$actual)
            }
          }
  
          expect version ${version}
          expect reproducible \$true
        "
      '';
    };
  }
  
negative.code: { lib, buildGoModule, fetchFromGitHub, runCommand }:
  
  buildGoModule rec {
    pname = "elvish";
  