Reset config options in between tests

The settings tests were causing tests in other files to fail
depending on the order they were run in. We'll reset the config
values after each expectation.

spec/omniauth/builder_spec.rb

@@ -9,9 +9,17 @@ describe OmniAuth::Builder do
     it 'calls original when rack 1.4' do
       allow(Rack).to receive(:release).and_return('1.4.0')
 
-      expect(builder).to receive(:new).with(app).and_call_original
+      expect(builder).to receive(:new).with(app, &prok).and_call_original
 
-      builder.new(app)
+      builder.new(app, &prok)
+    end
+
+    it 'calls original when rack 2' do
+      allow(Rack).to receive(:release).and_return('2.0.0')
+
+      expect(builder).to receive(:new).with(app, &prok).and_call_original
+
+      builder.new(app, &prok)
     end
   end
 
@@ -66,9 +74,11 @@ describe OmniAuth::Builder do
     it 'passes the block to the config' do
       prok = proc {}
 
-      OmniAuth::Builder.new(nil).on_failure(&prok)
+      with_config_reset(:on_failure) do
+        OmniAuth::Builder.new(nil).on_failure(&prok)
 
-      expect(OmniAuth.config.on_failure).to eq(prok)
+        expect(OmniAuth.config.on_failure).to eq(prok)
+      end
     end
   end
 
@@ -76,9 +86,11 @@ describe OmniAuth::Builder do
     it 'passes the block to the config' do
       prok = proc {}
 
-      OmniAuth::Builder.new(nil).before_options_phase(&prok)
+      with_config_reset(:before_options_phase) do
+        OmniAuth::Builder.new(nil).before_options_phase(&prok)
 
-      expect(OmniAuth.config.before_options_phase).to eq(prok)
+        expect(OmniAuth.config.before_options_phase).to eq(prok)
+      end
     end
   end
 
@@ -86,9 +98,11 @@ describe OmniAuth::Builder do
     it 'passes the block to the config' do
       prok = proc {}
 
-      OmniAuth::Builder.new(nil).before_request_phase(&prok)
+      with_config_reset(:before_request_phase) do
+        OmniAuth::Builder.new(nil).before_request_phase(&prok)
 
-      expect(OmniAuth.config.before_request_phase).to eq(prok)
+        expect(OmniAuth.config.before_request_phase).to eq(prok)
+      end
     end
   end
 
@@ -96,9 +110,11 @@ describe OmniAuth::Builder do
     it 'passes the block to the config' do
       prok = proc {}
 
-      OmniAuth::Builder.new(nil).before_callback_phase(&prok)
+      with_config_reset(:before_callback_phase) do
+        OmniAuth::Builder.new(nil).before_callback_phase(&prok)
 
-      expect(OmniAuth.config.before_callback_phase).to eq(prok)
+        expect(OmniAuth.config.before_callback_phase).to eq(prok)
+      end
     end
   end
 
@@ -127,4 +143,10 @@ describe OmniAuth::Builder do
       expect(app).to have_received(:call).with(env)
     end
   end
+
+  def with_config_reset(option)
+    old_config = OmniAuth.config.send(option)
+    yield
+    OmniAuth.config.send("#{option}=", old_config)
+  end
 end