Simplify endpoint block execution and deprecate return call in it

Author: ericproulx

spec/grape/endpoint_spec.rb

@@ -785,29 +785,13 @@ def memoized
       return 'Hello'
     end
 
+    expect(Grape.deprecator).to receive(:warn).with('Using `return` in an endpoint has been deprecated.')
+
     get '/home'
     expect(last_response.status).to eq(200)
     expect(last_response.body).to eq('Hello')
   end
 
-  describe '.generate_api_method' do
-    it 'raises NameError if the method name is already in use' do
-      expect do
-        described_class.generate_api_method('version', &proc {})
-      end.to raise_error(NameError)
-    end
-
-    it 'raises ArgumentError if a block is not given' do
-      expect do
-        described_class.generate_api_method('GET without a block method')
-      end.to raise_error(ArgumentError)
-    end
-
-    it 'returns a Proc' do
-      expect(described_class.generate_api_method('GET test for a proc', &proc {})).to be_a Proc
-    end
-  end
-
   context 'filters' do
     describe 'before filters' do
       it 'runs the before filter if set' do