[docs] Set up Danger to warn about updating changed docs on other versions

.circleci/config.yml

@@ -822,6 +822,10 @@ jobs:
       - update_submodules
       - yarn_install:
           working_directory: docs
+      - run:
+          name: Run Danger
+          working_directory: docs
+          command: yarn danger ci
       - yarn:
           command: export
           working_directory: docs

docs/dangerfile.js

@@ -0,0 +1,52 @@
+import { warn } from 'danger';
+import fs from 'fs';
+
+function warnIfOnlyOneVersionChanged() {
+  const LATEST_VERSION = JSON.parse(fs.readFileSync('./package.json')).version;
+
+  function getPageName(path) {
+    let version = getVersionFromPath(path);
+    return path.replace('docs/pages/versions/', '').replace(`${version}/`, '');
+  }
+
+  function getVersionFromPath(path) {
+    return path.replace('docs/pages/versions/', '').split('/')[0];
+  }
+
+  let pages = danger.git.modified_files.filter(
+    file => file.startsWith('docs/pages') && file.endsWith('.md')
+  );
+
+  let groupedByName = pages.reduce((all, path) => {
+    let pageName = getPageName(path);
+    all[pageName] = all[pageName] || [];
+    all[pageName].push(path);
+    return all;
+  }, {});
+
+  function getSuggestion(version, name) {
+    if (version === 'unversioned') {
+      let path = `docs/pages/versions/v${LATEST_VERSION}/${name}`;
+      let url = `https://github.com/expo/expo/blob/master/${path}`;
+      return `Please consider copying the changes to the [latest released version](${url}) if applicable.`;
+    } else if (version === `v${LATEST_VERSION}`) {
+      let path = `docs/pages/versions/unversioned/${name}`;
+      let url = `https://github.com/expo/expo/blob/master/${path}`;
+      return `Please make sure this change won't be lost on the next SDK release by updating the [unversioned copy](${url}).`;
+    } else {
+      return `You may also want to make these changes to other versions of the documentation, where applicable, in the [docs/pages/versions](https://github.com/expo/expo/tree/master/docs/pages/versions) directory.`;
+    }
+  }
+
+  Object.keys(groupedByName).forEach(name => {
+    let changes = groupedByName[name];
+    if (changes.length === 1) {
+      let version = getVersionFromPath(changes[0]);
+      warn(
+        `You modified \`${name}\` in the \`${version}\` directory. ${getSuggestion(version, name)}`
+      );
+    }
+  });
+}
+
+warnIfOnlyOneVersionChanged();

docs/package.json

@@ -37,8 +37,9 @@
   },
   "devDependencies": {
     "broken-link-checker": "^0.7.8",
+    "danger": "^9.2.10",
     "http-server": "^0.11.1",
     "minimist": "^1.2.0",
     "prettier": "^1.18.2"
   }
-}
+}

docs/pages/versions/unversioned/sdk/art.md

@@ -7,5 +7,3 @@ This library has been removed as of SDK 36. You likely want to use [Svg](../svg/
 If you need to use [react-native-progress](https://github.com/oblador/react-native-progress), which relies on ART, you can use the bare workflow and install [`@react-native-community/art`](https://github.com/react-native-community/art), or implement your own progress indicator using Svg ([here's an example](https://github.com/bartgryszko/react-native-circular-progress)).
 
 **Again, you almost definitely want to use [Svg](../svg/) instead of this unless you are really sure you want to use ART for some reason.**
-
-#

docs/pages/versions/v36.0.0/sdk/art.md

@@ -6,6 +6,4 @@ This library has been removed as of SDK 36. You likely want to use [Svg](../svg/
 
 If you need to use [react-native-progress](https://github.com/oblador/react-native-progress), which relies on ART, you can use the bare workflow and install [`@react-native-community/art`](https://github.com/react-native-community/art), or implement your own progress indicator using Svg ([here's an example](https://github.com/bartgryszko/react-native-circular-progress)).
 
-**Again, you almost definitely want to use [Svg](../svg/) instead of this unless you are really sure you want to use ART for some reason.**
-
-#
+**Again, you almost definitely want to use [Svg](../svg/) instead of this unless you are really sure you want to use ART for some reason.**