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## `fail`

### Signature

```solidity
function fail() internal virtual;
function fail(string memory message) internal virtual;
```

### Description

Mark the current test as failed when execution reaches a branch that should not run. Use `fail()` without a message, or `fail("reason")` to include a custom assertion message.

The message overload requires **forge-std v1.10.0 or later**. If you use an older forge-std dependency, use `fail()` or `assertTrue(false, "reason")`, or update the dependency with `forge update forge-std`. Updating the Forge binary alone does not update your project's forge-std library.

### Examples

Both tests below intentionally fail. The second includes a custom message:

```solidity [test/Fail.t.sol]
// [!include ~/snippets/projects/fail_assertions/test/Fail.t.sol]
```

Run the example from `src/snippets/projects/fail_assertions`:

```bash
$ forge install --no-git foundry-rs/forge-std@v1.10.0
$ forge test -vv
```

Expect two failed tests and a nonzero exit status.