ruby-grape/grape · error · ArgumentError

a block is required

Error message

a block is required

What it means

Grape::Testing::RunBeforeEach lets tests register endpoint setup hooks with `before_each`, which must be given a block to store. Calling `before_each` without a block (e.g. intending to query or reset hooks) raises ArgumentError ('a block is required') instead of silently registering nothing.

Source

Thrown at lib/grape/testing.rb:14

# frozen_string_literal: true

module Grape
  module Testing
    module RunBeforeEach
      def run
        self.class.run_before_each(self)
        super
      end
    end

    module ClassMethods
      def before_each(&block)
        raise ArgumentError, 'a block is required' unless block

        @before_each ||= []
        @before_each << block
      end

      def reset_before_each
        @before_each&.clear
      end

      def run_before_each(endpoint)
        superclass.run_before_each(endpoint) unless self == Grape::Endpoint
        @before_each&.each { |blk| blk.call(endpoint) }
      end
    end

    Grape::Endpoint.prepend(RunBeforeEach)
    Grape::Endpoint.extend(ClassMethods)
  end

View on GitHub (pinned to 22d7975629)

Solutions

1. Always pass a block: `before_each { |endpoint| endpoint.stub :helper, :value }`.
2. To clear hooks, call `reset_before_each` instead of a bare before_each.
3. When the block is optional in your own helpers, guard with `before_each(&block) if block`.

Example fix

# before
before_each # raises

# after
before_each { |endpoint| endpoint.instance_variable_set(:@current_user, user) }
reset_before_each # when you need to clear instead

before_each(&block) if block # conditional registration
reset_before_each # clearing hooks instead of a bare before_each

def block_given?(...) = block_given? # use Ruby's block_given? before calling before_each

When it happens

Trigger: `before_each` bare inside an RSpec setup. `before_each(&:stub_something)`-style shorthand that yields nil instead of a block. Guard code that calls before_each conditionally with the block accidentally dropped.

Common situations: Conditionally adding test hooks where the block variable is nil. Refactoring specs from blocks to method references and losing the `&`. Copying spec boilerplate incompletely.

Related errors

• type #{type} should support coercion via `[]`
• #declared is not available prior to parameter validation
• Representation of type #{representation.class} cannot be mer
• Status code must be Integer or Symbol.
• Argument must be a file path

AI-assisted analysis of ruby-grape/grape@22d7975629 (2026-08-21). Data as JSON: /api/errors/a4c43177b72eaa5f. Report an issue: GitHub.