Fix a bug where Method objects were not returned for setters inherited (#1688)

from a default (Pry::Config::Default). Eg, this is no longer an error:
[1] pry(main)> Pry.config.method(:exception_whitelist=)

CHANGELOG.md

@@ -16,6 +16,14 @@
 
 #### Bug fixes
 
+* Fix a bug where Method objects were not returned for setters inherited
+  from a default (Pry::Config::Default). Eg, this is no longer an error:
+
+      pry(main)> d = Pry::Config.from_hash({}, Pry::Config::Default.new)
+      pry(main)> d.method(:exception_whitelist=) # Error
+
+See pull request [#1688](https://github.com/pry/pry/pull/1688).
+
 * Do not capture unused Proc objects in Text helper methods `no_color` and `no_paging`,
   for performance reasons. Improve the documentation of both methods.
 

lib/pry/config/behavior.rb

@@ -188,6 +188,7 @@ module Pry::Config::Behavior
   end
 
   def respond_to_missing?(key, include_all=false)
+    key = key.to_s.chomp(ASSIGNMENT)
     key?(key) or @default.respond_to?(key) or super(key, include_all)
   end
 

spec/config_spec.rb

@@ -45,7 +45,7 @@ describe Pry::Config do
       expect(local3.foo).to eq(21)
     end
 
-    it "stores a local copy of the parent's hooks upon accessing them" do
+    it "stores a local copy of the parents hooks upon accessing them" do
       parent = Pry::Config.from_hash(hooks: "parent_hooks")
       local  = Pry::Config.new parent
       local.hooks.gsub! 'parent', 'local'
@@ -67,13 +67,7 @@ describe Pry::Config do
     end
 
     it "recursively builds Pry::Config objects from a Hash" do
-      h = {
-        'foo1' => {
-          'foo2' => {
-            'foo3' => 'foobar'
-          }
-        }
-      }
+      h = {'foo1' => {'foo2' => {'foo3' => 'foobar'}}}
       default = Pry::Config.from_hash(h)
       expect(default.foo1).to be_instance_of(described_class)
       expect(default.foo1.foo2).to be_instance_of(described_class)
@@ -92,6 +86,11 @@ describe Pry::Config do
       expect(method_obj.name).to eq :key
       expect(method_obj.call).to eq(1)
     end
+
+    it "returns a Method object for a setter on a parent" do
+      config = described_class.from_hash({}, described_class.from_hash(foo: 1))
+      expect(config.method(:foo=)).to be_an_instance_of(Method)
+    end
   end
 
   describe "#respond_to?" do