fix: suppress network requests when blocked

see #181

Author: gyoshev

src/Network.ts

@@ -109,14 +109,23 @@ export default class Network {
         }
       }
     }
-    xhr.open(method, url, true)
-    xhr.setRequestHeader('Content-Type', 'text/plain') // Avoid pre-flight.
-    xhr.send(data)
-    setTimeout(() => {
-      if (!handled) {
-        xhr.abort()
+    var blocked = false
+    xhr.onerror = xhr.ontimeout = () => {
+      if (xhr.status === 0) {
+        blocked = true
+        this.requestQueue.splice(0, this.requestQueue.length)
       }
-    }, this.networkTimeoutSeconds * 1000)
+    }
+    if (!blocked) {
+      xhr.open(method, url, true)
+      xhr.setRequestHeader('Content-Type', 'text/plain') // Avoid pre-flight.
+      xhr.send(data)
+      setTimeout(() => {
+        if (!handled) {
+          xhr.abort()
+        }
+      }, this.networkTimeoutSeconds * 1000)
+    }
   }
 
   /**

test/mocks/external.ts

@@ -31,3 +31,12 @@ xhrMock.resolveRequest = function() {
     jest.runAllTimers()
   }
 }
+
+xhrMock.blockRequest = function() {
+  const xhr = xhrQueue.shift()
+  if (xhr) {
+    xhr.status = 0
+    xhr.onerror()
+    jest.runAllTimers()
+  }
+}

test/specs/Network.test.ts

@@ -22,8 +22,24 @@ describe(Network, () => {
 
     xhrMock.resolveRequest()
     xhrMock.resolveRequest()
+    jest.runAllTimers()
 
     expect(success).toHaveBeenCalledTimes(2)
     expect(error).toHaveBeenCalledTimes(0)
   })
+
+  it('stops sending requests if they are blocked', () => {
+    jest.useFakeTimers()
+    const success = jest.fn()
+    const error = jest.fn()
+
+    network.ajax('POST', 'http://test.com/', {}, success, error, true, true)
+    xhrMock.blockRequest()
+    network.ajax('POST', 'http://test.com/', {}, success, error, true, true)
+
+    jest.runAllTimers()
+
+    expect(success).toHaveBeenCalledTimes(0)
+    expect(error).toHaveBeenCalledTimes(0)
+  })
 })