karatelabs/karate · critical · RuntimeException

ext ' ': ReportAssets.js(...) is required

Error message

ext '<name>': ReportAssets.js(...) is required

What it means

ReportAssets.validateAndBind checks each registered report extension spec at Suite boot: a spec without a JS entry is invalid because the extension has no client-side code to run. The failure is deliberately thrown at boot so misconfigured extensions fail the whole Suite early.

Solutions

1. Call .js("classpath:my-ext.js") (or relative path) on the ReportAssets spec before registration
2. Verify the js path points at an existing classpath resource — the next validation step requires it
3. Check that every registered spec in registerReportAssets completes its builder chain with js(...)

Example fix

// before
ReportAssets.named("my-ext").css("style.css")
// after
ReportAssets.named("my-ext").js("ext/my-ext.js").css("ext/style.css")

void check(ReportAssets a) { if (!a.toString().contains("js")) throw new IllegalStateException("spec missing js()"); }
// simpler: enforce in your own builder wrapper that js(...) is always called before registerReportAssets

try { suite.registerReportAssets(specs); } catch (RuntimeException e) { if (e.getMessage().contains("ReportAssets.js(...) is required")) { log.error("Extension spec missing js(): {}", e.getMessage()); } throw e; }

When it happens

Trigger: Registering a ReportAssets spec via registerReportAssets without calling .js(path), or calling js("") / js(" ").

Common situations: Building the spec conditionally and skipping the js() call; renaming an extension and forgetting its JS registration; copying a spec template with the js() line removed.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• ext ' ': points at missing resource
• embed(): each 'parts' entry must be an object
• embed(): each part needs a 'role'
• embed(): part ' ' needs 'data', 'path', or 'url
• ReportAssets.named: name is null or empty

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/186c46088cfbdffe. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/core/ReportAssets.java:169

    /** The ext-supplied CTA label, or null if this ext registered none. */
    public String ctaLabel() {
        return ctaLabel;
    }

    /** The ext-supplied CTA href, or null if this ext registered none. */
    public String ctaHref() {
        return ctaHref;
    }

    /**
     * Validate the spec against {@code classLoader} and bind it for later copying.
     * Throws (failing the Suite at boot) when {@code js} is unset or a referenced
     * resource is missing.
     */
    void validateAndBind(ClassLoader classLoader) {
        if (js == null || js.isBlank()) {
            throw new RuntimeException("ext '" + name + "': ReportAssets.js(...) is required");
        }
        requireResource(classLoader, js, "js");
        if (css != null) {
            requireResource(classLoader, css, "css");
        }
        for (String a : assets) {
            requireResource(classLoader, a, "asset");
        }
        for (Page p : pages) {
            if (p.href() != null) {
                requireResource(classLoader, p.href(), "page");
            }
        }
        this.classLoader = classLoader;
    }

    /**
     * Copy the declared assets (JS, optional CSS, page HTML) into {@code extDir}

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