add coverage job to azure pipeline

azure-pipelines.yml

@@ -20,6 +20,29 @@ jobs:
     workingDirectory: '$(system.defaultWorkingDirectory)'
     displayName: 'Test'
 
+- job: Linux Coverage
+  dependsOn: Linux
+
+  pool:
+    vmImage: 'Ubuntu 16.04'
+
+  variables:
+    GOPATH: '$(system.defaultWorkingDirectory)'
+
+  steps:
+  - checkout: none
+  - script: |
+      go version
+      go get -v -t -d v2ray.com/core/...
+      go get -v -t -d v2ray.com/ext/...
+    workingDirectory: '$(system.defaultWorkingDirectory)'
+    displayName: 'Fetch sources'
+  - script: |
+      cd ./src/v2ray.com/core
+      bash ./testing/coverage/coverall
+    workingDirectory: '$(system.defaultWorkingDirectory)'
+    displayName: 'Coverage'
+
 - job: MacOS
 
   pool: