Viewing github.com/facebook/react/fixtures/dom/src/toWarnDev.js

// copied from scripts/jest/matchers/toWarnDev.js

```
'use strict';
```

const {diff: jestDiff} = require('jest-diff');

```
const util = require('util');
```

function shouldIgnoreConsoleError(format, args) {

```
  if (__DEV__) {
```
```
    if (typeof format === 'string') {
```

      if (format.indexOf('Error: Uncaught [') === 0) {

        // This looks like an uncaught error from invokeGuardedCallback() wrapper

        // in development that is reported by jsdom. Ignore because it's noisy.

```
        return true;
```
```
      }
```

      if (format.indexOf('The above error occurred') === 0) {

        // This looks like an error addendum from ReactFiberErrorLogger.

```
        // Ignore it too.
```
```
        return true;
```
```
      }
```
```
    }
```
```
  } else {
```
```
    if (
```
```
      format != null &&
```

      typeof format.message === 'string' &&

      typeof format.stack === 'string' &&

```
      args.length === 0
```
```
    ) {
```

      // In production, ReactFiberErrorLogger logs error objects directly.

      // They are noisy too so we'll try to ignore them.

```
      return true;
```
```
    }
```
```
  }
```
```
  // Looks legit
```
```
  return false;
```
```
}
```
```
function normalizeCodeLocInfo(str) {
```

  return str && str.replace(/at .+?:\d+/g, 'at **');

```
}
```

const createMatcherFor = consoleMethod =>

  function matcher(callback, expectedMessages, options = {}) {

```
    if (__DEV__) {
```

      // Warn about incorrect usage of matcher.

      if (typeof expectedMessages === 'string') {

        expectedMessages = [expectedMessages];

      } else if (!Array.isArray(expectedMessages)) {

```
        throw Error(
```

          `toWarnDev() requires a parameter of type string or an array of strings ` +

            `but was given ${typeof expectedMessages}.`

```
        );
```
```
      }
```
```
      if (
```
```
        options != null &&
```

        (typeof options !== 'object' || Array.isArray(options))

```
      ) {
```
```
        throw new Error(
```

          'toWarnDev() second argument, when present, should be an object. ' +

            'Did you forget to wrap the messages into an array?'

```
        );
```
```
      }
```
```
      if (arguments.length > 3) {
```

        // `matcher` comes from Jest, so it's more than 2 in practice

```
        throw new Error(
```

          'toWarnDev() received more than two arguments. ' +

            'Did you forget to wrap the messages into an array?'

```
        );
```
```
      }
```

      const withoutStack = options.withoutStack;

      const warningsWithoutComponentStack = [];

      const warningsWithComponentStack = [];

```
      const unexpectedWarnings = [];
```

      let lastWarningWithMismatchingFormat = null;

      let lastWarningWithExtraComponentStack = null;

      // Catch errors thrown by the callback,

      // But only rethrow them if all test expectations have been satisfied.

      // Otherwise an Error in the callback can mask a failed expectation,

      // and result in a test that passes when it shouldn't.

```
      let caughtError;
```

      const isLikelyAComponentStack = message =>

        typeof message === 'string' && message.includes('\n    in ');

      const consoleSpy = (format, ...args) => {

        // Ignore uncaught errors reported by jsdom

        // and React addendums because they're too noisy.

```
        if (
```
```
          consoleMethod === 'error' &&
```

          shouldIgnoreConsoleError(format, args)

```
        ) {
```
```
          return;
```
```
        }
```

        const message = util.format(format, ...args);

        const normalizedMessage = normalizeCodeLocInfo(message);

        // Remember if the number of %s interpolations

        // doesn't match the number of arguments.

        // We'll fail the test if it happens.

```
        let argIndex = 0;
```

        format.replace(/%s/g, () => argIndex++);

        if (argIndex !== args.length) {

          lastWarningWithMismatchingFormat = {

```
            format,
```
```
            args,
```

            expectedArgCount: argIndex,

```
          };
```
```
        }
```

        // Protect against accidentally passing a component stack

        // to warning() which already injects the component stack.

```
        if (
```
```
          args.length >= 2 &&
```

          isLikelyAComponentStack(args[args.length - 1]) &&

          isLikelyAComponentStack(args[args.length - 2])

```
        ) {
```

          lastWarningWithExtraComponentStack = {

```
            format,
```
```
          };
```
```
        }
```

        for (let index = 0; index < expectedMessages.length; index++) {

          const expectedMessage = expectedMessages[index];

```
          if (
```

            normalizedMessage === expectedMessage ||

            normalizedMessage.includes(expectedMessage)

```
          ) {
```

            if (isLikelyAComponentStack(normalizedMessage)) {

              warningsWithComponentStack.push(normalizedMessage);

```
            } else {
```

              warningsWithoutComponentStack.push(normalizedMessage);

```
            }
```

            expectedMessages.splice(index, 1);

```
            return;
```
```
          }
```
```
        }
```
```
        let errorMessage;
```

        if (expectedMessages.length === 0) {

```
          errorMessage =
```

            'Unexpected warning recorded: ' +

            this.utils.printReceived(normalizedMessage);

        } else if (expectedMessages.length === 1) {

```
          errorMessage =
```

            'Unexpected warning recorded: ' +

            jestDiff(expectedMessages[0], normalizedMessage);

```
        } else {
```
```
          errorMessage =
```

            'Unexpected warning recorded: ' +

            jestDiff(expectedMessages, [normalizedMessage]);

```
        }
```

        // Record the call stack for unexpected warnings.

        // We don't throw an Error here though,

        // Because it might be suppressed by ReactFiberScheduler.

        unexpectedWarnings.push(new Error(errorMessage));

```
      };
```

      // TODO Decide whether we need to support nested toWarn* expectations.

      // If we don't need it, add a check here to see if this is already our spy,

```
      // And throw an error.
```

      const originalMethod = console[consoleMethod];

      // Avoid using Jest's built-in spy since it can't be removed.

      console[consoleMethod] = consoleSpy;

```
      try {
```
```
        callback();
```
```
      } catch (error) {
```
```
        caughtError = error;
```
```
      } finally {
```

        // Restore the unspied method so that unexpected errors fail tests.

        console[consoleMethod] = originalMethod;

        // Any unexpected Errors thrown by the callback should fail the test.

        // This should take precedence since unexpected errors could block warnings.

```
        if (caughtError) {
```
```
          throw caughtError;
```
```
        }
```

        // Any unexpected warnings should be treated as a failure.

        if (unexpectedWarnings.length > 0) {

```
          return {
```

            message: () => unexpectedWarnings[0].stack,

```
            pass: false,
```
```
          };
```
```
        }
```

        // Any remaining messages indicate a failed expectations.

        if (expectedMessages.length > 0) {

```
          return {
```
```
            message: () =>
```

              `Expected warning was not recorded:\n  ${this.utils.printReceived(

```
                expectedMessages[0]
```
```
              )}`,
```
```
            pass: false,
```
```
          };
```
```
        }
```

        if (typeof withoutStack === 'number') {

          // We're expecting a particular number of warnings without stacks.

          if (withoutStack !== warningsWithoutComponentStack.length) {

```
            return {
```
```
              message: () =>
```

                `Expected ${withoutStack} warnings without a component stack but received ${warningsWithoutComponentStack.length}:\n` +

                warningsWithoutComponentStack.map(warning =>

                  this.utils.printReceived(warning)

```
                ),
```
```
              pass: false,
```
```
            };
```
```
          }
```

        } else if (withoutStack === true) {

          // We're expecting that all warnings won't have the stack.

          // If some warnings have it, it's an error.

          if (warningsWithComponentStack.length > 0) {

```
            return {
```
```
              message: () =>
```

                `Received warning unexpectedly includes a component stack:\n  ${this.utils.printReceived(

                  warningsWithComponentStack[0]

                )}\nIf this warning intentionally includes the component stack, remove ` +

                `{withoutStack: true} from the toWarnDev() call. If you have a mix of ` +

                `warnings with and without stack in one toWarnDev() call, pass ` +

                `{withoutStack: N} where N is the number of warnings without stacks.`,

```
              pass: false,
```
```
            };
```
```
          }
```

        } else if (withoutStack === false || withoutStack === undefined) {

          // We're expecting that all warnings *do* have the stack (default).

          // If some warnings don't have it, it's an error.

          if (warningsWithoutComponentStack.length > 0) {

```
            return {
```
```
              message: () =>
```

                `Received warning unexpectedly does not include a component stack:\n  ${this.utils.printReceived(

                  warningsWithoutComponentStack[0]

                )}\nIf this warning intentionally omits the component stack, add ` +

                `{withoutStack: true} to the toWarnDev() call.`,

```
              pass: false,
```
```
            };
```
```
          }
```
```
        } else {
```
```
          throw Error(
```

            `The second argument for toWarnDev(), when specified, must be an object. It may have a ` +

              `property called "withoutStack" whose value may be undefined, boolean, or a number. ` +

              `Instead received ${typeof withoutStack}.`

```
          );
```
```
        }
```

        if (lastWarningWithMismatchingFormat !== null) {

```
          return {
```
```
            message: () =>
```
```
              `Received ${
```

                lastWarningWithMismatchingFormat.args.length

              } arguments for a message with ${

                lastWarningWithMismatchingFormat.expectedArgCount

              } placeholders:\n  ${this.utils.printReceived(

                lastWarningWithMismatchingFormat.format

```
              )}`,
```
```
            pass: false,
```
```
          };
```
```
        }
```

        if (lastWarningWithExtraComponentStack !== null) {

```
          return {
```
```
            message: () =>
```

              `Received more than one component stack for a warning:\n  ${this.utils.printReceived(

                lastWarningWithExtraComponentStack.format

              )}\nDid you accidentally pass a stack to warning() as the last argument? ` +

              `Don't forget warning() already injects the component stack automatically.`,

```
            pass: false,
```
```
          };
```
```
        }
```
```
        return {pass: true};
```
```
      }
```
```
    } else {
```

      // Any uncaught errors or warnings should fail tests in production mode.

```
      callback();
```
```
      return {pass: true};
```
```
    }
```
```
  };
```
```
module.exports = {
```

  toLowPriorityWarnDev: createMatcherFor('warn'),

  toWarnDev: createMatcherFor('error'),

```
};
```