message: Clears screen during watch mode correctly.
diff: @@ -16,6 +16,8 @@ const ansiEscapes = require('ansi-escapes');
  const chalk = require('chalk');
  const createContext = require('./lib/createContext');
  const HasteMap = require('jest-haste-map');
  +const isCI = require('is-ci');
  +const isInteractive = process.stdout.isTTY && !isCI;
  const isValidPath = require('./lib/isValidPath');
  const preRunMessage = require('./preRunMessage');
  const runJest = require('./runJest');
  @@ -86,7 +88,7 @@ const watch = (
  }
  testWatcher = new TestWatcher({isWatchMode: true});
  - pipe.write(CLEAR);
  + isInteractive && pipe.write(CLEAR);
  preRunMessage.print(pipe);
  isRunning = true;
  return runJest(
  