fwserver: validate each ListResult

Author: bbasata

internal/fwserver/server_listresource.go

@@ -85,19 +85,47 @@ func (s *Server) ListResource(ctx context.Context, fwReq *ListRequest, fwStream
 	logging.FrameworkTrace(ctx, "Called provider defined ListResource")
 
 	if stream.Results == nil {
-		// If the provider returned a nil results stream, we treat it as an empty stream.
+		// If the provider returned a nil results stream, we return an empty stream.
 		stream.Results = func(func(list.ListResult) bool) {}
 	}
 
-	fwStream.Results = listResourceEventStreamAdapter(stream.Results)
+	fwStream.Results = processListResults(req, stream.Results)
 }
 
-func listResourceEventStreamAdapter(stream iter.Seq[list.ListResult]) iter.Seq[ListResult] {
-	// TODO: is this any more efficient than a for-range?
+func processListResults(req list.ListRequest, stream iter.Seq[list.ListResult]) iter.Seq[ListResult] {
 	return func(yieldFw func(ListResult) bool) {
-		yield := func(event list.ListResult) bool {
-			return yieldFw(ListResult(event))
+		for result := range stream {
+			var fwResult ListResult
+
+			diags := validateListResult(req, result)
+			if diags.HasError() {
+				fwResult = ListResult{Diagnostics: diags}
+			} else {
+				fwResult = ListResult(result)
+			}
+			if !yieldFw(fwResult) {
+				return
+			}
 		}
-		stream(yield)
 	}
 }
+
+func validateListResult(req list.ListRequest, result list.ListResult) diag.Diagnostics {
+	var diags diag.Diagnostics
+
+	if result.Identity == nil {
+		diags.AddError(
+			"Incomplete List Result",
+			"ListResult.Identity is nil.",
+		)
+	}
+
+	if req.IncludeResource && result.Resource == nil {
+		diags.AddWarning(
+			"Incomplete List Result",
+			"ListRequest.IncludeResource is true and ListResult.Resource is nil.",
+		)
+	}
+
+	return diags
+}