Behavioral Change Detection

Why this rule exists

A line removed from production code is a behavior change. If no test changed in the same diff, either the removed line was untested (silent regression risk) or the test it broke was deleted to make CI green.

Code example

// Removes a guard clause without touching tests
- if (user is null) throw new ArgumentNullException(nameof(user));
  return user.Email;

// Removes the guard AND adds a test asserting the new contract
- if (user is null) throw new ArgumentNullException(nameof(user));
  return user.Email;
+ // tests/UserTests.cs
+ [Fact] public void GetEmail_NullUser_Throws_NullReference() { ... }

Configuration

Disable or adjust the severity of this rule in .gauntletci.json:

{
  "rules": {
    "GCI0003": { "enabled": true, "severity": "Block" }
  }
}

See Configuration for the full schema.

Related rules

Discussed in

Real-world evidence