When passing lambda as body, to to_return_json, it is evaluated at th…

…e time of returning the response and not at the time of declaration.

lib/webmock/request_stub.rb

@@ -32,12 +32,25 @@ def to_return_json(*response_hashes)
       json_response_hashes = [*response_hashes].flatten.map do |resp_h|
         headers, body = resp_h.values_at(:headers, :body)
 
-        body = body.call if body.respond_to?(:call)
-        body = body.to_json unless body.is_a?(String)
+        json_body = if body.respond_to?(:call)
+          ->(request_signature) {
+            b = if body.respond_to?(:arity) && body.arity == 1
+              body.call(request_signature)
+            else
+              body.call
+            end
+            b = b.to_json unless b.is_a?(String)
+            b
+          }
+        elsif !body.is_a?(String)
+          body.to_json
+        else
+          body
+        end
 
         resp_h.merge(
           headers: {content_type: 'application/json'}.merge(headers.to_h),
-          body: body
+          body: json_body
         )
       end
 

spec/acceptance/shared/returning_declared_responses.rb

@@ -136,6 +136,25 @@ def call(request)
       end
     end
 
+    describe "when response was declared via to_return_json" do
+      describe "and declared response body is lamba" do
+        it "should evaluate the response body at the time of returning the response" do
+          record = double("SomeRecord")
+          allow(record).to receive_messages(to_json: '{"what":"something callable"}.')
+
+          stub_request(:get, "www.example.com").to_return_json(body: -> {record})
+
+          allow(record).to receive_messages(to_json: '{"what":"something else callable"}.')
+          expect(http_request(:get, "http://www.example.com/").body).to eq('{"what":"something else callable"}.')
+        end
+
+        it "should evaluate the response body with request passed as argument to lambda" do
+          stub_request(:get, "www.example.com").to_return_json(body: ->(request) {"\"#{request.uri.to_s}\""})
+          expect(http_request(:get, "http://www.example.com/").body).to eq("\"http://www.example.com:80/\"")
+        end
+      end
+    end
+
     describe "when response was declared as lambda" do
       it "should return evaluated response body" do
         stub_request(:post, "www.example.com").to_return(lambda {|request|

spec/unit/request_stub_spec.rb

@@ -87,12 +87,24 @@
       expect(@request_stub.response.body).to eq('{"abc":"def"}')
     end
 
-    it "should json-ify any callable proc or lambda to body" do
+    it "should evaluate a callable proc or lambda body at the time of response being returned and not at the time of stub declaration" do
+      record = double("SomeRecord")
+      allow(record).to receive_messages(to_json: '{"what":"something callable"}.')
+
+      @request_stub.to_return_json(body: (->(request) { record }))
+
+      allow(record).to receive_messages(to_json: '{"what":"something else callable"}.')
+      expect(@request_stub.response.body.call(double(WebMock::RequestSignature))).to eq('{"what":"something else callable"}.')
+    end
+
+    it "should evaluate a callable proc or lambda body, even if it takes no args" do
       record = double("SomeRecord")
       allow(record).to receive_messages(to_json: '{"what":"something callable"}.')
 
       @request_stub.to_return_json(body: -> { record })
-      expect(@request_stub.response.body).to eq('{"what":"something callable"}.')
+
+      allow(record).to receive_messages(to_json: '{"what":"something else callable"}.')
+      expect(@request_stub.response.body.call(double(WebMock::RequestSignature))).to eq('{"what":"something else callable"}.')
     end
 
     it "should apply the content_type header" do