**Do you want to request a _feature_ or report a _bug_?**

Report a bug.

**What is the current behavior?**

When testing components, `Warning: ReactComponentTreeDevtool: Missing React element for debugID 1 when building stack` is shown when calling `TestUtils.renderIntoDocument`.

**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar (template: https://jsfiddle.net/reactjs/69z2wepo/).**

https://github.com/angusfretwell/reproduce-debugid-warning (`npm install && npm test`).

**What is the expected behavior?**

According to #7187 this is an internal warning and shouldn't be displayed.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
- react@15.2.1
- react-addons-test-utils@15.2.1
- react-dom@15.2.1

I didn't receive this warning on 15.2.0.

var nonEmptyStatusDisplays = stripEmptyValues(statusDisplays);
  var nonEmptyStatusProps = stripEmptyValues(props.usernameToStatus);
  var username;
  expect(Object.keys(nonEmptyStatusDisplays).length)
    .toEqual(Object.keys(nonEmptyStatusProps).length);
  for (username in nonEmptyStatusDisplays) {
    if (!nonEmptyStatusDisplays.hasOwnProperty(username)) {
      continue;
    }
    expect(nonEmptyStatusDisplays[username].getStatus())
      .toEqual(nonEmptyStatusProps[username]);
  }
  
  for (username in nonEmptyStatusProps) {
    if (!nonEmptyStatusProps.hasOwnProperty(username)) {
      continue;
    }
    expect(nonEmptyStatusDisplays[username].getStatus())
      .toEqual(nonEmptyStatusProps[username]);
  }
  expect(Object.keys(nonEmptyStatusDisplays))
      .toEqual(Object.keys(nonEmptyStatusProps));
}
/**
 * For all statusDisplays that existed in the previous iteration of the
 * sequence, verify that the state has been preserved. `StatusDisplay` contains
 * a unique number that allows us to track internal state across ordering
 * movements.
 */
function verifyStatesPreserved(lastInternalStates, statusDisplays) {