Expect-tslint

npm install --save-dev expect-tslint

Custom tslint rules

There are two tslint rules, no-expect-in-catch and chai-terminated. Add the rule to your tslint.json rules section and add expect-tslint to the rulesDirectory.

no-expect-in-catch

Will error if there are expect calls in a catch handler or in promise catch method. An expect call is a method call with one or two arguments with name expect. The name can be changed through the options. Include expect if you want to match against it.

{
  "rules": {
    "no-expect-in-catch": {
      "options": {"aliases": ["expect", "should"]}
    }
  },
  "rulesDirectory": ["expect-tslint"]
}

Note that the following will not be considered an expect call with either rule.

something.expect(someArg);

chai-terminated

Will error if

expect(somethingToExpect);

or if the chain is not terminated. The chain is terminated by a method call ( there is no checking that this is a valid method) or by one of the following properties : 'ok', 'true', 'false', 'null', 'undefined', 'NaN', 'exist', 'empty', 'Arguments','arguments', 'extensible', 'sealed', 'frozen', 'finite'

Through options it is possible to provide additional terminal properties, such as rejected or fulfilled if using chai-as-promised.

{
  "rules": {
    "chai-terminated": {
      "options": {"additionalTerminals": ["rejected", "fulfilled"]}
    }
  },
  "rulesDirectory": ["expect-tslint"]
}

With this rule, an expect call is the same as for no-expect-in-catch with method name expect or should.

Controlling the walk

Both rules are set up to not forEachChild for specific SyntaxKind. These can be found at ignoreKinds.ts.

Through options it is possible exclude further SyntaxKind or include ones that I have excluded.

Use cases:

1. I have excluded InterfaceDeclaration but it is possible that you have applied a decorator ( that you will custom transform later) and need to check it.

e.g

function FakeDecorator(fake:any){}

// @ts-ignore
@FakeDecorator(() => {
  expect('this');
})
interface IDecoratedInterface {}

2. For some strange reason there are a lot of classes and you know it is safe to ignore them.

To include and exclude use the includeExcludeKinds options property. ** do not use ts.SyntaxKind... **

{
  "rules": {
    "chai-terminated": {
      "options": {
        "includeExcludeKinds": {
          "exclude": ["ClassDeclaration"],
          "include": ["InterfaceDeclaration"]
        }
      }
    }
  },
  "rulesDirectory": ["expect-tslint"]
}