Json-ify any non-string object in #to_return_json

README.md

@@ -330,6 +330,16 @@ stub_request(:any, "www.example.com").
 Net::HTTP.get('www.example.com', '/')    # ===> "abc\n"
 ```
 
+### Response with JSON body
+
+```ruby
+
+stub_request(:any, "www.example.com").
+  to_return_json(body: {foo: "bar"})
+
+Net::HTTP.get('www.example.com', '/') # ===> "{\"foo\": \"bar\"}"
+```
+
 ### Response with custom status message
 
 ```ruby

lib/webmock/request_stub.rb

@@ -29,9 +29,13 @@ 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)
+
         resp_h.merge(
           headers: {content_type: 'application/json'}.merge(headers.to_h),
-          body: body.is_a?(Hash) ? body.to_json : body
+          body: body
         )
       end
 

spec/unit/request_stub_spec.rb

@@ -69,6 +69,32 @@
       expect(@request_stub.response.status).to eq([500, ""])
     end
 
+    it "should json-ify an Array body" do
+      @request_stub.to_return_json(body: [{abc: "def" }])
+      expect(@request_stub.response.body).to eq('[{"abc":"def"}]')
+    end
+
+    it "should json-ify any object responding to `to_json`" do
+      record = double("SomeRecord")
+      allow(record).to receive_messages(to_json: '{"what":"something"}.')
+
+      @request_stub.to_return_json(body: record)
+      expect(@request_stub.response.body).to eq('{"what":"something"}.')
+    end
+
+    it "should not over-json-ify a String body" do
+      @request_stub.to_return_json(body: '{"abc":"def"}')
+      expect(@request_stub.response.body).to eq('{"abc":"def"}')
+    end
+
+    it "should json-ify any callable proc or lambda to body" 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"}.')
+    end
+
     it "should apply the content_type header" do
       @request_stub.to_return_json(body: {abc: "def"}, status: 500)
       expect(@request_stub.response.headers).to eq({"Content-Type"=>"application/json"})