What causes "Invalid test reporter: '${input}'. Valid reporters: ' '." in apple/pkl?

Use one of the exact reporter names listed in the error message (lowercase)

apple/pkl · error · InvalidUserDataException

Invalid test reporter

Error message

Invalid test reporter: '${input}'. Valid reporters: '<each reporter name, lowercase>'.

What it means

toTestReporter converts a user-supplied test reporter name into a TestReporter enum value. If the input does not match any known reporter (case-insensitively), it throws InvalidUserDataException listing all valid reporter names in lowercase.

Solutions

Use one of the exact reporter names listed in the error message (lowercase)
Check the plugin documentation or TestReporter enum for the valid set
Fix casing/typo in the reporter string in the build script
If a reporter seems missing, verify you are on a plugin version that supports it

Example fix

// before
testReporters = listOf("junit-xmlx")
// after
testReporters = listOf("junit-xml")

Defensive patterns

Strategy: validation

Validate before calling

// Java: validate against the enum before assignment
boolean valid = java.util.Arrays.stream(TestReporter.values())
    .anyMatch(r -> r.name().toLowerCase(java.util.Locale.ROOT).equals(input.toLowerCase(java.util.Locale.ROOT)));

Try / catch

try {
  task.getTestReporters().add(PluginUtils.toTestReporter(input));
} catch (InvalidUserDataException e) {
  logger.error("Invalid reporter '{}'; use one of: {}", input, e.getMessage());
  throw new GradleException(e.getMessage());
}

Prevention

Copy reporter names from the error message's valid list verbatim
Check the TestReporter enum in the plugin version you use — names can change between versions
Keep reporter configuration in a shared convention plugin to avoid typos

When it happens

Trigger: Setting the testReports/test reporter property on Pkl Test tasks with a name not in the reporter enum (e.g. "junitxml" instead of "junit-xml" or whatever the enum defines).

Common situations: Typo in build.gradle testReporter setting, guessing reporter names, migrating CI configs from other tools (jest/mocha naming), or case/format mismatches.

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 apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/29003c79d042c543. Report an issue: GitHub.

Appendix: source

Thrown at pkl-gradle/src/main/java/org/pkl/gradle/utils/PluginUtils.java:204

    try {
      return TestReporter.valueOf(inputStr.toUpperCase(Locale.ROOT));
    } catch (IllegalArgumentException e) {
      var sb = new StringBuilder("Invalid test reporter: '");
      sb.append(inputStr).append("'. ");
      sb.append("Valid reporters: ");
      var isFirst = true;
      // `enumEntries()` is not available in Kotlin versions below 1.8
      //noinspection EnumValuesSoftDeprecateInJava
      for (var value : TestReporter.values()) {
        if (isFirst) {
          isFirst = false;
        } else {
          sb.append(", ");
        }
        sb.append('\'').append(value.toString().toLowerCase(Locale.ROOT)).append('\'');
      }
      sb.append(".");
      throw new InvalidUserDataException(sb.toString());
    }
  }
}

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