benhartley/mutant

# Mutation plugins
Mutations are provided to `mutant` via plugins. These take the form of a module that exports a function that accepts a single `stateMask` argument and return a [visitor](https://github.com/thejameskyle/babel-handbook/blob/master/translations/en/plugin-handbook.md#visitors) that `babel-traverse` can use to modify the AST of the code being mutated.

They can be enabled / disabled via the [configuration file](../../../README.md#config).

# Currently available plugins

### `boolean-literal-flip`
Inverts the truthiness of the value of a `BooleanLiteral`

``` javascript
const trueThing = true;
// becomes:
const trueThing = false;
```

### `gt-to-gte`
Replaces an instance of the `BinaryExpression` operator `>` with `>=`

``` javascript
if (x > y) {}
// becomes:
if (x >= y) {}
```

### `gte-to-gt`
Replaces an instance of the `BinaryExpression` operator `>=` with `>`

``` javascript
if (x >= y) {}
// becomes:
if (x > y) {}
```

### `lt-to-lte`
Replaces an instance of the `BinaryExpression` operator `<` with `<=`

``` javascript
if (x < y) {}
// becomes:
if (x <= y) {}
```

### `lte-to-lt`
Replaces an instance of the `BinaryExpression` operator `<=` with `<`

``` javascript
if (x <= y) {}
// becomes:
if (x < y) {}
```

### `minus-to-plus`
Replaces an instance of the `BinaryExpression` operator `-` with `+`

``` javascript
const x = 2 - 1;
// becomes:
const x = 2 + 1;
```

### `plus-to-minus`
Replaces an instance of the `BinaryExpression` operator `+` with `-`

``` javascript
const x = 2 + 1;
// becomes:
const x = 2 - 1;
```