Warn when text/content is checked for nil

lib/capybara/queries/text_query.rb

@@ -6,11 +6,17 @@ module Capybara
     class TextQuery < BaseQuery
       def initialize(type = nil, expected_text, session_options:, **options) # rubocop:disable Style/OptionalArguments
         @type = type.nil? ? default_type : type
-        @expected_text = expected_text.is_a?(Regexp) ? expected_text : expected_text.to_s
         @options = options
         super(@options)
         self.session_options = session_options
 
+        if expected_text.nil? && !exact?
+          warn 'Checking for expected text of nil is confusing and/or pointless since it will always match. '\
+               'Please specify a string or regexp instead.'
+        end
+
+        @expected_text = expected_text.is_a?(Regexp) ? expected_text : expected_text.to_s
+
         @search_regexp = Capybara::Helpers.to_regexp(@expected_text, exact: exact?)
 
         assert_valid_keys

lib/capybara/spec/session/has_text_spec.rb

@@ -139,6 +139,12 @@ Capybara::SpecHelper.spec '#has_text?' do
     expect(@session).to have_text(nil)
   end
 
+  it 'should warn when passed nil' do
+    @session.visit('/with_html')
+    expect_any_instance_of(Kernel).to receive(:warn).with(/Checking for expected text of nil is confusing/) # rubocop:disable RSpec/AnyInstance
+    expect(@session).to have_text(nil)
+  end
+
   it 'should wait for text to appear', requires: [:js] do
     Capybara.using_wait_time(3) do
       @session.visit('/with_js')