sdk: readable clients (no Empty wrapper, no unused error module), documented examples with tests

sdk/src/discovery.rs

@@ -68,25 +68,31 @@ pub fn method<P: Params, R: SchemaType>(doc: &mut Value, name: &str, docs: &str)
             "schema": field,
         })
     }).collect();
-    doc["x-sdk-input"]
-        .as_object_mut()
-        .unwrap()
-        .extend(definitions);
+    if !params.is_empty() {
+        doc["x-sdk-input"]
+            .as_object_mut()
+            .unwrap()
+            .extend(definitions);
+    }
     let mut output = generator(true);
     let result_schema = serde_json::to_value(output.subschema_for::<R>()).unwrap();
     doc["x-sdk-output"]
         .as_object_mut()
         .unwrap()
         .extend(output.take_definitions(true));
-    doc["methods"].as_array_mut().unwrap().push(json!({
+    let has_params = !params.is_empty();
+    let mut method = json!({
         "name":name,
         "summary":docs.split("\n\n").next().unwrap_or_default(),
         "description":docs,
         "paramStructure":"by-name",
         "params":params,
         "result":{"name":"result","schema":result_schema},
-        "x-sausage-params":params_ref,
-    }));
+    });
+    if has_params {
+        method["x-sausage-params"] = params_ref;
+    }
+    doc["methods"].as_array_mut().unwrap().push(method);
 }
 
 /// Resolve shared schema names after all methods contribute their contracts.