karatelabs/karate · error · RuntimeException

karate.callSingle() requires at least one argument (path)

Error message

karate.callSingle() requires at least one argument (path)

What it means

karate.callSingle() needs at least one argument: the path of the feature or JS file to execute once per suite. Karate throws this when the call has zero arguments, because there is no target to run or cache.

Solutions

  1. Supply the path as the first argument: karate.callSingle('classpath:utils.js').
  2. If extra data is needed, pass it as the second argument: karate.callSingle(path, arg).
  3. Assert the path variable is non-empty before invoking (karate.log or a fail-fast check).

Example fix

// before
karate.callSingle();

// after
karate.callSingle('classpath:utils/token.js');
Defensive patterns

Strategy: validation

Validate before calling

if (!path || typeof path !== 'string') { throw new Error('callSingle path required'); } karate.callSingle(path);

Type guard

function isValidPath(p) { return typeof p === 'string' && p.trim().length > 0; }

Try / catch

try { karate.callSingle(path); } catch (e) { if (String(e.message).includes('requires at least one argument')) { karate.log('callSingle missing path'); } throw e; }

Prevention

When it happens

Trigger: `karate.callSingle()` invoked with no arguments; a path variable that is undefined/null at call time and not passed through.

Common situations: Refactoring call expressions and losing the argument; conditional paths that resolve to nothing; copy-paste of callSingle without its target path.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/3fc7eb27739909f2. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/core/KarateJsBase.java:408

                throw new RuntimeException("karate.callonce() requires at least one argument (feature path)");
            }
            String path = args[0].toString();
            Object arg = args.length > 1 ? args[1] : null;
            return rt.executeJsCallOnce(path, arg);
        };
    }

    /**
     * karate.callSingle() - Execute a feature/JS file once per Suite and cache the result.
     */
    JavaInvokable callSingle() {
        return args -> {
            ScenarioRuntime rt = getRuntime();
            if (rt == null) {
                throw new RuntimeException("karate.callSingle() is not available in this context");
            }
            if (args.length == 0) {
                throw new RuntimeException("karate.callSingle() requires at least one argument (path)");
            }
            String path = args[0].toString();
            Object arg = args.length > 1 ? args[1] : null;
            return rt.executeCallSingle(path, arg);
        };
    }

    /**
     * karate.configure() - Apply configuration from JavaScript.
     */
    JavaInvokable configure() {
        return args -> {
            if (args.length < 2) {
                throw new RuntimeException("configure() needs two arguments: key and value");
            }
            String key = args[0].toString();
            Object value = args[1];
            ScenarioRuntime rt = getRuntime();

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