# Handles oauth2 authentication scheme

This test validates that the emitter can handle a basic authentication scheme correctly, including the client signature and its initialization

## Typespec

The spec contains a simple service with a Bearer authentication scheme

```tsp
@service(#{ title: "Test Service" })
@useAuth(
  OAuth2Auth<
    [
      {
        type: OAuth2FlowType.clientCredentials,
        tokenUrl: "https://api.example.com/oauth2/authorize",
        refreshUrl: "https://api.example.com/oauth2/refresh",
      }
    ],
    ["read"]
  >
)
namespace Test;

@route("/valid")
@get
op valid(): NoContentResponse;
```

## TypeScript

### Client

The client signature should include a positional parameter for credential of type KeyCredential. A basic auth token is a key credential that gets put into the Authorization header

```ts src/testClient.ts class TestClient
export class TestClient {
  #context: TestClientContext;
  constructor(
    endpoint: string,
    credential: OAuth2TokenCredential<ClientCredentialsFlow>,
    options?: TestClientOptions,
  ) {
    this.#context = createTestClientContext(endpoint, credential, options);
  }
  async valid(options?: ValidOptions) {
    return valid(this.#context, options);
  }
}
```

### ClientContext

The client context should setup the pipeline to use the credential in the Authorization header.

```ts src/api/testClientContext.ts function createTestClientContext
export function createTestClientContext(
  endpoint: string,
  credential: OAuth2TokenCredential<ClientCredentialsFlow>,
  options?: TestClientOptions,
): TestClientContext {
  const params: Record<string, any> = {
    endpoint: endpoint,
  };
  const resolvedEndpoint = "{endpoint}".replace(/{([^}]+)}/g, (_, key) =>
    key in params
      ? String(params[key])
      : (() => {
          throw new Error(`Missing parameter: ${key}`);
        })(),
  );
  return getClient(resolvedEndpoint, {
    ...options,
    credential,
    authSchemes: [
      {
        kind: "oauth2",
        flows: [
          {
            kind: "clientCredentials",
            tokenUrl: "https://api.example.com/oauth2/authorize",
            refreshUrl: "https://api.example.com/oauth2/refresh",
            scopes: ["read"],
          },
        ],
      },
    ],
  });
}
```