Set the "Accept" request header to the specified type, rathern than a…

src/SwaggerProvider.DesignTime/v3/OperationCompiler.fs

@@ -252,7 +252,7 @@ type OperationCompiler(schema: OpenApiDocument, defCompiler: DefinitionCompiler,
                                 [ if not(isNull payloadMime) then
                                       "Content-Type", payloadMime
                                   if not(isNull retMime) then
-                                      "Accept", MediaTypes.ApplicationJson ]
+                                      "Accept", retMime ]
                             @>
 
                         // Locates parameters matching the arguments

tests/SwaggerProvider.ProviderTests/v3/Swashbuckle.ReturnTextControllers.Tests.fs

@@ -19,3 +19,12 @@ let ``Return text/csv GET Test``() =
 [<Fact>]
 let ``Send & return text/plain POST Test``() =
     api.PostApiConsumesText("hello") |> asyncEqual "hello"
+
+// Test for https://github.com/fsprojects/SwaggerProvider/pull/290 to check for expected 'Accept' header values
+[<Fact>]
+let ``Return text/plain Accept header Test``() =
+    api.GetApiCheckAcceptsPlain() |> asyncEqual "Hello world"
+
+[<Fact>]
+let ``Return text/csv Accept header Test``() =
+    api.GetApiCheckAcceptsCsv() |> asyncEqual "Hello,world"

tests/Swashbuckle.WebApi.Server/Controllers/ReturnTextControllers.fs

@@ -21,6 +21,32 @@ type ReturnCsvController() =
     member this.Get() =
         "Hello,world" |> ActionResult<string>
 
+// CheckAcceptsPlainController and CheckAcceptsCsvController are tests for https://github.com/fsprojects/SwaggerProvider/pull/290
+//    to test that the generated 'Accept' headers contain the expected values
+[<Route("api/[controller]")>]
+[<ApiController>]
+type CheckAcceptsPlainController() =
+    inherit ControllerBase()
+
+    [<HttpGet; Produces("text/plain")>]
+    member this.Get() =
+        if this.Request.Headers.Accept.Equals("text/plain") then
+            "Hello world" |> ActionResult<string>
+        else
+            ActionResult<string>(UnsupportedMediaTypeResult())
+
+[<Route("api/[controller]")>]
+[<ApiController>]
+type CheckAcceptsCsvController() =
+    inherit ControllerBase()
+
+    [<HttpGet; Produces("text/csv")>]
+    member this.Get() =
+        if this.Request.Headers.Accept.Equals("text/csv") then
+            "Hello,world" |> ActionResult<string>
+        else
+            ActionResult<string>(UnsupportedMediaTypeResult())
+
 [<Route("api/[controller]")>]
 [<ApiController>]
 type ConsumesTextController() =