extending @types/jasmine interface / namespace doesn't recognise method

I’m using ts-node via jasmine-ts and have a custom matcher which extends the d.ts in @types\jasmine unfortunately ts-node doesn’t seem to pick up the new method.

I’m adding my method to the interface like so:

   declare namespace jasmine {
    interface Matchers<T> {
        toEqualInstruction(expected: IInstruction): boolean;
    }
   }

but ts-node reports:

c:\github\gareththegeek\corewar>npm test

> corewar@1.0.0 test c:\github\gareththegeek\corewar
> nyc jasmine-ts


c:\github\gareththegeek\corewar\node_modules\ts-node\src\index.ts:307
        throw new TSError(formatDiagnostics(diagnosticList, cwd, ts, lineOffset))
              ^
TSError: ⨯ Unable to compile TypeScript
simulator\tests\ExecutiveTests.ts (227,38): Property 'toEqualInstruction' does not exist on type 'Matchers<IInstruction>'. (2339)
simulator\tests\ExecutiveTests.ts (230,38): Property 'toEqualInstruction' does not exist on type 'Matchers<IInstruction>'. (2339)

I’ve posted this on SO here: https://stackoverflow.com/questions/47313578/cannot-extend-a-types-jasmine-interface in case this is not the right place for the issue.

All the info I’ve found says to do what I’ve done but I’m unable to work out quite why the interface isn’t being combined.

I see this issue in vscode intellisense as well so it may be more a .ts issue. Happy to help investigate to get to the bottom of things.

versions below if it’s of any help:

>ts-node --version
ts-node v3.3.0
node v8.9.1
typescript v2.6.1

[blakeembrey]

It works fine for me. There’s plenty of instructions around and unfortunately ts-node isn’t the best place to find them.

1. It needs to be in a separate .d.ts file because if it’s in the same .ts file all you’re doing is declaring a local namespace (it’s a confusing part of TypeScript, but once you add import or export to the top level of a .ts file it’s a module now, no longer interacting with the global scope)
2. You need to actually include the extra .d.ts file in compilation. The normal way to do that is by including it via tsconfig.json. You can, however, also use a reference.

Here’s the test that worked locally for me:

npm i @types/jasmine

declare namespace jasmine {
    export interface Matchers<T> {
        toEqualInstruction(expected: any): boolean;
    }
}

/// <reference path="interfaces.d.ts" />

expect(10).toEqualInstruction(10)

tsc test.ts

[blakeembrey]

Thanks, I was just responding that you missed that point 😄

One thing you try try if you need the import is wrapping it all in declare global {}. Haven’t tested it yet, but it might work for your use-case.