The constants MIN_LENGTH_THRESHOLD and SINGLE_WORD_ANTIPATTERNS are defined at the top level (global namespace) instead of being scoped within a module or the matcher definition. This can lead to namespace pollution and potential conflicts with other code that might use similar constant names.

Consider moving these constants inside the matcher definition or wrapping them in a module namespace. For example, you could define them as class-level constants within a module, or define them as constants within the matcher block itself.

As I mentioned in my comment :

Doing a quick run to see all the failures first

So, this is actually part of the process :)

The match block is not correctly evaluating whether the content exists in the flash messages. The code calls have_content expected within the within_flash_messages block, but this just returns a matcher object without evaluating it. Since matcher objects are always truthy, this will always return true (assuming validation passes).

The match block should actually check if the content exists. Consider using one of these approaches:

1. Use Capybara's predicate methods: page.has_content?(expected)
2. Delegate to Capybara's built-in matcher and return the result of checking the scoped element
3. Use an expectation and return true/false based on whether it passes

For example, you could capture the result within the within_flash_messages block by checking if the current scope has the content.

This PR introduces antipattern detection that will cause hundreds of existing tests to fail. A search of the codebase shows 206+ instances of have_admin_callout("successfully") and many more instances of similar antipatterns like have_admin_callout("updated"), have_admin_callout("created"), etc.

The PR description states "Do the search and see it on 0" suggesting all instances should be fixed, but this PR doesn't include any fixes to the affected test files. This will cause a massive test failure across the entire codebase once merged.

This is a breaking change that requires one of the following approaches:

1. Include fixes for all affected tests in this same PR
2. Split into two PRs: first fix all the antipattern usages, then add the validation
3. Add a temporary flag or environment variable to enable/disable the antipattern detection, allowing for gradual migration
4. Provide a clear migration guide and accept that tests will fail until they're updated

Without addressing this, merging this PR will break the CI/CD pipeline and block development until all affected tests are fixed.

⚠️ Potential issue | 🟠 Major

# First, let's read the entire file to understand the context
cat -n decidim-dev/lib/decidim/dev/test/rspec_support/admin_callout_matchers.rb

# Search for within_flash_messages definition
rg -n "def within_flash_messages" --type ruby

# Search for how within_flash_messages is used elsewhere in the codebase
rg -n "within_flash_messages" --type ruby -A 2 | head -50

# Search for other RSpec.Matchers.define patterns in the codebase to see how match blocks are typically structured
rg -n "RSpec::Matchers\.define" --type ruby -A 10 | head -100

# Look for examples of match blocks in custom matchers
rg -n "match do" --type ruby -A 3 | grep -E "(match do|expect|has_|\.call)" | head -50

# Verify that have_content is an RSpec matcher that needs expect() to be evaluated
rg -n "have_content" decidim-dev/lib/decidim/dev/test/rspec_support/helpers.rb

Match block returns unevaluated matcher instead of boolean assertion

The have_content expected statement inside within_flash_messages only builds a matcher object and returns it without evaluating the assertion. RSpec matcher objects are truthy, so the block will always pass regardless of whether the text is actually present. Wrap the assertion with expect() or use a boolean method like has_text?() to properly evaluate the condition.

  match do |_page|
    # Short-circuit for nil/symbols to avoid calling within_flash_messages
    return true if expected.nil? || expected.is_a?(Symbol)

    validate_text(expected)

    within_flash_messages do
-     have_content expected
+     page.has_text?(expected)
    end
  end

In `@decidim-dev/lib/decidim/dev/test/rspec_support/admin_callout_matchers.rb`
around lines 30 - 38, The match block currently returns an unevaluated RSpec
matcher (have_content expected) which always passes; inside the
within_flash_messages block (and keeping validate_text(expected) and the
surrounding match do |_page| intact) replace the matcher construction with a
boolean check such as has_text?(expected) (i.e., call has_text?(expected) inside
within_flash_messages) so the block returns a true/false based on actual
presence of the text rather than a matcher object.