fix: make operarions middleware proper express handler

lib/middleware/operation.js

@@ -54,31 +54,29 @@ function mapOperations ({ api, res, method }) {
   })
 }
 
-function findOperation (operationMiddleware) {
-  return async function (req, res, next) {
-    const method = req.method === 'HEAD' ? 'GET' : req.method
+function findOperations (req, res, next) {
+  const method = req.method === 'HEAD' ? 'GET' : req.method
 
-    let operations = mapOperations({ api: req.hydra.api, res, method })
-      .filter(({ operation }) => operation)
-
-    if (operationMiddleware) {
-      operations = operationMiddleware(operations, { req, res })
-    }
+  req.hydra.operations = mapOperations({ api: req.hydra.api, res, method })
+    .filter(({ operation }) => operation)
 
-    if (!operations.length) {
-      return next()
-    }
-
-    if (operations.length > 1) {
-      error('Multiple operations found')
-      return next(new Error('Ambiguous operation'))
-    }
+  return next()
+}
 
-    const [{ resource, operation }] = operations
-    req.hydra.resource = resource
-    req.hydra.operation = operation
+function prepareOperation (req, res, next) {
+  if (!req.hydra.operations.length) {
     return next()
   }
+
+  if (req.hydra.operations.length > 1) {
+    error('Multiple operations found')
+    return next(new Error('Ambiguous operation'))
+  }
+
+  const [{ resource, operation }] = req.hydra.operations
+  req.hydra.resource = resource
+  req.hydra.operation = operation
+  return next()
 }
 
 async function invokeOperation (req, res, next) {
@@ -117,7 +115,13 @@ async function invokeOperation (req, res, next) {
 function factory (middleware = {}) {
   const router = Router()
 
-  router.use(findOperation(middleware.operations))
+  router.use(findOperations)
+
+  if (middleware.operations) {
+    router.use(middleware.operations)
+  }
+
+  router.use(prepareOperation)
 
   if (middleware.resource) {
     router.use(middleware.resource)

test/operation.test.js

@@ -94,7 +94,7 @@ describe('middleware/operation', () => {
       term: RDF.namedNode('/')
     })))
     const hooks = {
-      operations: sinon.stub().callsFake(operations => operations)
+      operations: sinon.stub().callsFake((req, res, next) => next())
     }
     app.use(middleware(hooks))