[Danger] Add some static check rules in dangerfile (#2676)

The check rules are described in https://github.com/apache/incubator-weex/blob/master/CONTRIBUTING.md#publish-your-change

.github/PULL_REQUEST_TEMPLATE.md

@@ -5,14 +5,15 @@ All PRs should be submitted to master branch -->
 <!-- Please follow the template below:
 * If you are going to fix a bug of Weex, check whether it already exists in [Github Issue](https://github.com/apache/incubator-weex/issues). If it exists, make sure to write down the link to the corresponding Github issue in the PR you are going to create.
 * If you are going to add a feature for weex, reference the following recommend procedure:
-    1. Writing a email to [mailing list](https://weex.io/guide/contribute/how-to-contribute.html#mailing-list) to talk about what you'd like to do.
-    1. Write the corresponding [document](https://weex.io/guide/contribute/how-to-contribute.html#contribute-code-or-document) -->
+    1. Writing a email to [mailing list](https://github.com/apache/incubator-weex/blob/master/CONTRIBUTING.md#mailing-list) to talk about what you'd like to do.
+    1. Write the corresponding [Documentation](https://github.com/apache/incubator-weex/blob/master/CONTRIBUTING.md#contribute-documentation) 
+    1. Write the corresponding Changelogs at the end of changelog.md -->
 
 
 # Brief Description of the PR
 
 # Checklist
-* [] Demo
-* [] Document
+* Demo:
+* Documentation:
 
-<!-- # Additional content -->
+<!-- # Additional content -->

dangerfile.js

@@ -16,15 +16,64 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import { schedule, danger, fail, warn, message, markdown } from "danger";
+// Removed import
 import fs from "fs";
 import path from 'path';
 import GitHubApi from 'github';
 import parseDiff from 'parse-diff';
 
+// check if pr submitted to master branch
+console.log("checkMasterBranch")
+const isMergeRefMaster = danger.github.pr.base.ref === 'master';
+if(!isMergeRefMaster){
+  warn("You'd better to submit PR to master branch as the development of Weex is on master branch.");
+}
+
+// match regex line by line
+function matchRegex(pr_body,regex){
+  const lines = pr_body.split("\n");
+  for (let i = 0; i < lines.length; i++) {
+    if(lines[i].match(regex)){
+      return true;
+    }
+  }
+  return false;
+}
+
+var pr_body = danger.github.pr.body.toLowerCase();
+// Because Pr description template include the following line：
+// 1. Write the corresponding [documentation](https://github.com/apache/incubator-weex/blob/master/CONTRIBUTING.md#contribute-code-or-document)
+// so we should check the documentation below the ### checklist
+console.log("checkDocumentation");
+const index = pr_body.indexOf("checklist")
+const includeChecklist = (index!=-1)
+if(includeChecklist && !matchRegex(pr_body.substring(index),/documentation.*http/)){
+  const msg = "If you update the code, "+
+    "maybe you should update the documentation and add the documentation link in the PR description. \n" +
+    "here is the guide about how to contribute documentation:https://github.com/apache/incubator-weex/blob/master/CONTRIBUTING.md#contribute-code-or-document \n";
+  warn(msg);
+}
+
+// check if pr contains a demo link
+console.log("checkDemo");
+if(!matchRegex(pr_body,/demo.*http/)){
+  const msg =  "If your PR is about fixing a bug excluding crash the code,"+
+    "you should add the demo link in the PR description. \n "+
+    "here is a demo link:http://dotwe.org/vue?spm=a2c7j.-guide-contribute-contribute-code.0.0.3e93748cmxz3yt";
+  warn(msg);
+}
+
+// check if pr bind the github milestone
+console.log("checkMileStone");
+if(!danger.github.pr.milestone){
+  warn("Current pr not bind the milestone");
+}
+
 // Make sure there are changelog entries
 const hasChangelog = danger.git.modified_files.includes("changelog.md")
-if (!hasChangelog) { warn("No Changelog changes!") }
+if (!hasChangelog) { 
+  warn(`No Changelog changes! - <i>Can you add a Changelog? To do so,append your changes to the changelog.md</i>`);
+}
 
 const jsFiles = danger.git.created_files.filter(path => path.endsWith("js"));