Features

• Add an ignoring_check_for_db_index qualifier to the have_secure_token
  matcher, since has_secure_token encourages use of an index but does not
  enforce it. (#1278)

• Add allow_blank to validate_length_of to match other validation matchers.
  (#725, #1318)

• Add new matcher have_implicit_order_column which can be used to test the
  implicit_order_column setting for ActiveRecord models under Rails 6+.
  (#1243)

• Add a new is_other_than qualifier to validate_numericality_of to be able
  to test the numericality validation's :other_than option. (#1282)

• Add a new have_one_attached and have_many_attached matchers for testing
  the new model-level ActiveStorage macros in Rails 6. (#1102)

Bug fixes

• Fix performance of allow_value so that it doesn't hang if the given value is
  really long. (#1290)

• Fix have_many so that it is possible to test an association that has a scope
  that takes an argument. (#952, #992)

• Update validate_uniqueness_of to use the public validators_on instead of
  the private _validators when reading validations off of a model. This
  enables shoulda-matchers to be used with the schema_validations gem.
  (#995)

• Update validate_uniqueness_of to work with scopes that are time columns.
  (#1190)

• Fix have_and_belong_to_many so that when using the join_table qualifier
  you can pass a symbol rather than a string. (#1323)

Improvements

• Update have_many when used against a :through association so that it fails
  if the inverse model does not have a belongs_to association. (#646,
  #723, c0a1578)

• Add Ruby 2.7 to test matrix and default development Ruby. (#1310)

• Remove warnings emitted on Ruby 2.7 in word_wrap. (#1314)

• Remove warnings emitted on Ruby 2.7 in Doublespeak. (#1328)

• Clean up requires within the code by converting them to autoloads. (#1320)