xai-org/x-algorithm · error · SemanticCheckFailure

MockPass function expects either 1 arguments but %d received

Error message

MockPass function expects either 1 arguments but %d received

What it means

MockPass(fnName) takes exactly one string argument — the name of the function whose mock should be bypassed (pass through to the real implementation). Any other argument count fails.

Source

Thrown at botmaker/src/java/com/twitter/botmaker/compiler/Compiler.java:1256

        );
      }
    } catch (Exception e) {
      throw new SemanticCheckFailure(e);
    }

    return Constant.UNIT;
  }

  private ASTNode toMockPass(
      CompilerContext context,
      String exprText,
      Tree root) throws SemanticCheckFailure {
    try {
      if (root.getChildCount() == 2) {
        String funcName = toStringConstant(root.getChild(1));
        context.addMockPass(funcName);
      } else {
        throw new SemanticCheckFailure(
            String.format("MockPass function expects either 1 arguments but %d received",
                root.getChildCount() - 1)
        );
      }
    } catch (Exception e) {
      throw new SemanticCheckFailure(e);
    }

    return Constant.UNIT;
  }

  private ASTNode toMockPassAll(
      CompilerContext context,
      String exprText,
      Tree root) throws SemanticCheckFailure {
    try {
      if (root.getChildCount() == 2) {
        String packageName = toStringConstant(root.getChild(1));

View on GitHub (pinned to 24c60942c5)

Solutions

Call MockPass with exactly one function-name string literal
Double-check generated test scaffolding emits a single argument

Example fix

// before
MockPass("getScore", "otherFn")
// after
MockPass("getScore")

Defensive patterns

Strategy: validation

Validate before calling

if (mockPassArgs != 1) throw new IllegalArgumentException("MockPass takes exactly 1 arg");

Try / catch

catch (SemanticCheckFailure e) { if (e.getMessage().contains("MockPass")) fixArity(); else throw e; }

Prevention

Emit exactly one quoted function name for MockPass

When it happens

Trigger: `MockPass()` with no args, or `MockPass("a", "b")` with two; also passing a non-string node that makes the count check irrelevant after toStringConstant would throw, but arity errors surface first.

Common situations: Confusing MockPass with Mock argument shapes, or trailing commas/extra tokens in generated test setup expressions.

Related errors

AI-assisted analysis of xai-org/x-algorithm@24c60942c5 (2026-08-28). Data as JSON: /api/errors/64a209ef027a8c0e. Report an issue: GitHub.