# LS4001: Test Contains No Assertion

## Intent

LS4001 is a compiler check that reports a test method that contains no assertion, because a test that asserts nothing passes whatever the code does and proves nothing about the scenario it names. This page states what the rule reports, where the error sits, and how to assert the result the test covers.

## Reference

### What the Rule Enforces

LS4001 enforces [Prove Each Scenario with a Test That Calls Its Use Case](https://litespec.dev/2.0.0/backend/dotnet/testing.md#prove-each-scenario-with-a-test-that-calls-its-use-case) (`litespec/backend/dotnet/testing#prove-each-scenario-with-a-test-that-calls-its-use-case`). It runs in test projects only. Its category is `LiteSpec.Tests`. It reports an error and is enabled by default, as the [Analyzers overview](https://litespec.dev/2.0.0/analyzers/README.md) describes.

### What the Rule Reports

The rule reports a method carrying a test attribute (`Fact`, `Theory`, `Test`, `TestCase`, `TestCaseSource`, `TestMethod`, or `DataTestMethod`) whose body calls no assertion. An assertion is a call to a member of a type named `Assert`, or to a method whose name starts with `Assert`. The diagnostic sits on the method name.

### Failing Example

```csharp
public sealed class OrderTests
{
    [Fact]
    public void Place_WhenDraft_MarksPlaced()
    {
        var order = new Order();
        order.Place();
    }
}
```

### Passing Example

```csharp
public sealed class OrderTests
{
    [Fact]
    public void Place_WhenDraft_MarksPlaced()
    {
        var order = new Order();
        order.Place();
        Assert.True(order.Placed);
    }
}
```

### How to Fix

Assert the result the test covers: the state, event, call, response, or refusal the scenario names.

## Notes

### What the Rule Ignores

The rule does not report methods without a test attribute, even in a test project. It counts an assertion anywhere in the test body, including inside a local function. It does not run outside test projects.