karatelabs/karate · error · RuntimeException

expect() - no such api:

Error message

expect() - no such api:

What it means

The base Expect object exposes only its whitelisted property keys (to, not, that/and/which, be/is, have/has, include/contain, equal/eql). Any other property access on an expect() result throws a RuntimeException naming the key.

Solutions

  1. Chain only through supported keys: to/not/and/that/which/be/have/include/contain/equal/eql
  2. Extract the subject for raw checks: expect(x).subject or use plain JS/Java comparisons
  3. Fix typos in chained keys

Example fix

// before
expect(x).eql({ a: 1 }) // no such api: eqls? — use supported chain
// after
expect(x).to.eql({ a: 1 })
Defensive patterns

Strategy: type-guard

Validate before calling

// before chaining, verify the member is one of the Expect accessors
var expectKeys = ['to','not','that','and','which','be','is','have','has','include','contain','equal','eql'];
if (expectKeys.indexOf(key) < 0) throw 'unsupported expect() member: ' + key;

Type guard

function isExpect(o){ return o != null && o.getSubject !== undefined; } // check subject access before raw property reads

Try / catch

try { expect(x).to.equal(y); } catch (e) { if (e.message.indexOf('no such api') >= 0) karate.log('typo in expect chain: ' + e.message); else throw e; }

Prevention

When it happens

Trigger: Accessing an unknown member on expect(...), e.g. expect(x).length, expect(x).ok, expect(x).toThrow, or a typo like expect(x).eqls(...).

Common situations: Chai's property-style assertions (.ok, .true, .empty) accessed directly; typos; assuming expect() returns the raw subject instead of an assertion object.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/cbef178e4889f25d. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/match/Expect.java:518

        if ("not".equals(key)) {
            return new Expect(subject, true, onResult, throwOnFailure, contextSupplier);
        }
        if ("that".equals(key) || "and".equals(key) || "which".equals(key)) {
            return this; // language chains
        }
        if ("be".equals(key) || "is".equals(key)) {
            return expectToBe; // shorthand for .to.be
        }
        if ("have".equals(key) || "has".equals(key)) {
            return expectToHave; // shorthand for .to.have
        }
        if ("include".equals(key) || "contain".equals(key)) {
            return matchChainable(Match.Type.CONTAINS); // shorthand for .to.include / .to.contain
        }
        if ("equal".equals(key) || "eql".equals(key)) {
            return match(Match.Type.EQUALS); // shorthand for .to.equal / .to.eql
        }
        throw new RuntimeException("expect() - no such api: " + key);
    }

    // ========== Getters for Composition ==========

    public Object getSubject() {
        return subject;
    }

    public boolean isNegated() {
        return negated;
    }

    public BiConsumer<Context, Result> getOnResult() {
        return onResult;
    }

    public boolean isThrowOnFailure() {
        return throwOnFailure;

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