add failing test

Fixes: #1330

Author: sdelamo

function-aws-api-proxy/src/test/groovy/io/micronaut/function/aws/proxy/ContentTypeSpec.groovy

@@ -0,0 +1,59 @@
+package io.micronaut.function.aws.proxy
+
+import com.amazonaws.serverless.proxy.internal.testutils.AwsProxyRequestBuilder
+import com.amazonaws.serverless.proxy.internal.testutils.MockLambdaContext
+import com.amazonaws.serverless.proxy.model.AwsProxyResponse
+import com.amazonaws.services.lambda.runtime.Context
+import io.micronaut.context.ApplicationContext
+import io.micronaut.context.annotation.Requires
+import io.micronaut.http.HttpHeaders
+import io.micronaut.http.HttpMethod
+import io.micronaut.http.HttpStatus
+import io.micronaut.http.MediaType
+import io.micronaut.http.annotation.Body
+import io.micronaut.http.annotation.Controller
+import io.micronaut.http.annotation.Get
+import io.micronaut.http.annotation.Post
+import io.micronaut.http.annotation.Status
+import spock.lang.AutoCleanup
+import spock.lang.Shared
+import spock.lang.Specification
+
+class ContentTypeSpec extends Specification {
+    @Shared
+    @AutoCleanup
+    MicronautLambdaContainerHandler handler = new MicronautLambdaContainerHandler(
+            ApplicationContext.builder().properties([
+                    'spec.name'                 : 'ContentTypeSpec',
+                    'micronaut.security.enabled': false,
+            ])
+    )
+    @Shared
+    Context lambdaContext = new MockLambdaContext()
+
+    void "verify controllers return json by default"() {
+        given:
+        AwsProxyRequestBuilder builder = new AwsProxyRequestBuilder('/json/bydefault', HttpMethod.GET.toString())
+        builder.header(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON)
+
+        when:
+        AwsProxyResponse response = handler.proxy(builder.build(), lambdaContext)
+
+        then:
+        response.statusCode == 200
+        response.body == '{"msg":"Hello world"}'
+        response.headers
+        "application/json" == response.getHeaders().get("Content-Type")
+    }
+
+    @Controller('/json')
+    @Requires(property = 'spec.name', value = 'ContentTypeSpec')
+    static class BodyController {
+
+        @Get("/bydefault")
+        @Status(HttpStatus.OK)
+        Map<String, Object> index() {
+            [msg: "Hello world"]
+        }
+    }
+}