🔧 Add recursive Config#inherits_defaults?

Returns `true` when all attributes inherit from `Config.default`, the
version number (as a Rational) when all attributes inherit from a
versioned default, `nil` if any attributes inherit from `Config.global`
overrides (but not from non-global ancestors), or `false` when any
attributes have been overridden by `self` or an ancestor (besides global
or default configs),

Author: nevans

lib/net/imap/config/attr_inheritance.rb

@@ -73,6 +73,36 @@ def inherited?(*attrs)
           attrs.all? { data[_1] == INHERITED }
         end
 
+        # :call-seq:
+        #   inherits_defaults?(*attrs) -> true | Rational | nil | false
+        #
+        # Returns whether all +attrs+ are inherited from a default config.
+        # When no +attrs+ are given, returns whether *all* attributes are
+        # inherited from a default config.
+        #
+        # Returns +true+ when all attributes inherit from Config.default, the
+        # version number (as a Rational) when all attributes inherit from a
+        # versioned default (see Config@Versioned+defaults), +nil+ if any
+        # attributes inherit from Config.global overrides (but not from
+        # non-global ancestors), or +false+ when any attributes have been
+        # overridden by +self+ or an ancestor (besides global or default
+        # configs),
+        #
+        # Related: #overrides?
+        def inherits_defaults?(*attrs)
+          if equal?(Config.default)
+            true
+          elsif equal?(Config.global)
+            true if inherited?(*attrs)
+          elsif (v = AttrVersionDefaults::VERSIONS.find { equal? Config[_1] })
+            attrs  = DEFAULT_TO_INHERIT if attrs.empty?
+            attrs &= DEFAULT_TO_INHERIT
+            (attrs.empty? || parent.inherits_defaults?(*attrs)) && v
+          else
+            inherited?(*attrs) && parent.inherits_defaults?(*attrs)
+          end
+        end
+
         # :call-seq:
         #   overrides?(attr)   -> true or false
         #   overrides?(*attrs) -> true or false

test/net/imap/test_config.rb

@@ -349,6 +349,56 @@ def duck.to_r   = 1/11111
     assert child.inherited?(:debug, :idle_response_timeout, :open_timeout)
   end
 
+  test "#inherits_defaults?" do
+    assert_same true, Config.default.inherits_defaults?
+    assert_same true, Config.default.inherits_defaults?(:sasl_ir, :open_timeout)
+
+    assert_equal true, Config.global.inherits_defaults?
+    Config.version_defaults.each do |name, config|
+      version = config.inherits_defaults?
+      assert_kind_of Rational, version
+      assert_same Config[version], config
+      assert_same version, config.inherits_defaults?(:sasl_ir, :open_timeout)
+    end
+
+    Config.global.debug = false
+    assert_equal nil,  Config.global.inherits_defaults?
+    assert_equal true, Config.global.inherits_defaults?(:sasl_ir, :open_timeout)
+    Config.version_defaults.each do |name, config|
+      assert_equal nil, config.inherits_defaults?
+      version = config.inherits_defaults?(:sasl_ir, :open_timeout)
+      assert_kind_of Rational, version
+      assert_same Config[version], config
+    end
+
+    config = Config.new 0.5
+    assert_equal nil,  config.inherits_defaults?
+    Config.global.reset
+    assert_equal 0.5r, config.inherits_defaults?
+
+    config.debug = false
+    assert_equal false, config.inherits_defaults?
+    assert_equal 0.5r,  config.inherits_defaults?(:sasl_ir, :open_timeout)
+
+    child = config.new debug: true, sasl_ir: true
+    assert_equal false, child.inherits_defaults?
+    assert_equal false, child.inherits_defaults?(:sasl_ir, :open_timeout)
+    assert_equal 0.5r,  child.inherits_defaults?(:open_timeout)
+
+    Config.global.sasl_ir = true
+    Config.global.open_timeout = 111
+    # inherits defaults from 0.5
+    assert_equal false, config.inherits_defaults?
+    assert_equal 0.5r,  config.inherits_defaults?(:sasl_ir, :open_timeout)
+    config.reset
+    assert_equal 0.5r, config.inherits_defaults?
+    # inherits overrides from global
+    config = Config.new
+    assert_equal nil,  config.inherits_defaults?
+    assert_equal nil,  config.inherits_defaults?(:sasl_ir, :open_timeout)
+    assert_equal true, config.inherits_defaults?(:debug)
+  end
+
   test "#overrides?" do
     base = Config.new debug: false, open_timeout: 99, idle_response_timeout: 15
     child = base.new debug: true, open_timeout: 15, idle_response_timeout: 10