[ReactNative] Do flow check when running packager

packager/getFlowTypeCheckMiddleware.js

@@ -0,0 +1,86 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+var exec = require('child_process').exec;
+
+function getFlowTypeCheckMiddleware(options) {
+  return function(req, res, next) {
+    if (options.skipflow) {
+      return next();
+    }
+    if (options.flowroot || options.projectRoots.length === 1) {
+      var flowroot = options.flowroot || options.projectRoots[0];
+    } else {
+      console.warn('flow: No suitable root');
+      return next();
+    }
+    exec('command -v flow >/dev/null 2>&1', function(error, stdout) {
+      if (error) {
+        console.warn('flow: Skipping because not installed.  Install with ' +
+          '`brew install flow`.');
+        return next();
+      } else {
+        return doFlowTypecheck(res, flowroot, next);
+      }
+    });
+  };
+}
+
+function doFlowTypecheck(res, flowroot, next) {
+  var flowCmd = 'cd "' + flowroot + '" && flow --json --timeout 20';
+  var start = Date.now();
+  console.log('flow: Running static typechecks.');
+  exec(flowCmd, function(flowError, stdout) {
+    if (!flowError) {
+      console.log('flow: Typechecks passed (' + (Date.now() - start) + 'ms).');
+      return next();
+    } else {
+      try {
+        var flowResponse = JSON.parse(stdout);
+        var errors = [];
+        var errorNum = 1;
+        flowResponse.errors.forEach(function(err) {
+          // flow errors are paired across callsites, so we indent and prefix to
+          // group them
+          var indent = '';
+          err.message.forEach(function(msg) {
+            errors.push({
+              description: indent + 'E' + errorNum + ': ' + msg.descr,
+              filename: msg.path,
+              lineNumber: msg.line,
+              column: msg.start,
+            });
+            indent = '  ';
+          });
+          errorNum++;
+        });
+        var message = 'Flow found type errors.  If you think these are wrong, ' +
+          'make sure flow is up to date, or disable with --skipflow.';
+      } catch (e) {
+        var message =
+          'Flow failed to provide parseable output:\n\n`' + stdout + '`';
+        console.error(message, '\nException: `', e, '`\n\n');
+      }
+      var error = {
+        status: 500,
+        message: message,
+        type: 'FlowError',
+        errors: errors,
+      };
+      console.error('flow: Error running command `' + flowCmd + '`:\n', error);
+      res.writeHead(error.status, {
+        'Content-Type': 'application/json; charset=UTF-8',
+      });
+      res.end(JSON.stringify(error));
+    }
+  });
+}
+
+module.exports = getFlowTypeCheckMiddleware;