Support for node-fetch

[rmclaughlin-nelnet]

OpenAPI version
2 and/or 3?
3
Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
This looks like a great solution to a problem we have been facing. However, we use node-fetch exclusively in our code and tests. Do you have any plans to support node-fetch?
Describe the solution you'd like
A clear and concise description of what you want to happen.
Support for node-fetch

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

Are you going to resolve the issue?

[rwalle61]

Hi @rmclaughlin-nelnet, thanks for raising this! 😃

I've been meaning to support node-fetch for a while as it's pretty popular.

What's the error you get when passing a node-fetch response to the toSatisfyApiSpec assertion?

I expect the solution will be straightforward:

• add a test block for node-fetch responses here
• make a NodeFetchResponse class, similar to the AxiosResponseClass
• ensure our ResponseFactory can distinguish node-fetch responses from responses of other request packages.

I'll do this when I have time, if you want it sooner you're welcome to make a pull request

[rmclaughlin-nelnet]

Thanks for the response. Here is the error I get

TypeError: Cannot read property 'path' of undefined

      160 |     });
      161 |
    > 162 |     expect(res).toSatisfyApiSpec();
          |                 ^
      163 |   });
      164 | });
      165 |

      at Object.getPathname (node_modules/openapi-validator/lib/utils/common.utils.ts:13:21)
      at OpenApi3Spec.findExpectedPathItem (node_modules/openapi-validator/lib/classes/AbstractOpenApiSpec.ts:106:28)
      at OpenApi3Spec.findExpectedResponseOperation (node_modules/openapi-validator/lib/classes/AbstractOpenApiSpec.ts:113:33)
      at OpenApi3Spec.findExpectedResponse (node_modules/openapi-validator/lib/classes/AbstractOpenApiSpec.ts:80:44)
      at OpenApi3Spec.validateResponse (node_modules/openapi-validator/lib/classes/AbstractOpenApiSpec.ts:123:31)
      at Object.default_1 (node_modules/jest-openapi/src/matchers/toSatisfyApiSpec.ts:25:39)
      at Object.toSatisfyApiSpec (node_modules/jest-openapi/src/index.ts:28:31)
      at __EXTERNAL_MATCHER_TRAP__ (../../node_modules/expect/build/index.js:386:30)
      at Object.throwingMatcher [as toSatisfyApiSpec] (../../node_modules/expect/build/index.js:387:15)
      at Object.<anonymous> (e2e.test.js:162:17)

[rwalle61]

Thanks, also which version of node-fetch are you using? Looks like most people are on 2.6.5:

[rmclaughlin-nelnet]

Yes, we are on 2.6.x

[rwalle61]

hey, so node-fetch (2.6.5) is trickier to support than I expected because its response object (i.e. the result of await fetch(...)) is different to that of the request packages we already support (axios, superagent, request-promise). I found a workaround, see below. Let me know if it solves your immediate problem, and perhaps we can improve it or expose a new async matcher.

Problem

Firstly there is no sync method to access the node-fetch response body. It must be accessed via either await response.json() or await response.text() (depending on the header). So expect(await fetch(...)).toSatisfyApiSpec() won't work, we'll have to expose an asynchronous method (expect(response).toEventuallySatisfyApiSpec()?).

Secondly, the response does not include the original request method. We use this to find which OpenAPI response definition the actual node-fetch response should satisfy. So the matcher might have to be expect(response).toEventuallySatisfyApiSpec('GET').

Workaround (corrected on 30 Oct)
This works by parsing the response into a superagent-like response first:

describe('test', () => {
  it('passes', async () => {
    const rawResponse = await fetch('endpoint');
    const body = await rawResponse.json();
    const res = {
      req: {
        path: rawResponse.url,
        method: 'GET',
      },
      status: rawResponse.status,
      body,
      text: JSON.stringify(body),
    };
    expect(res).to.satisfyApiSpec;
  });
});

If you need to do lots of these, you can automate the parsing:

type HTTPMethod =
  | 'GET'
  | 'POST'
  | 'PUT'
  | 'DELETE'
  | 'OPTIONS'
  | 'HEAD'
  | 'PATCH';

type ParsedResponse = {
  req: {
    path: string;
    method: HTTPMethod;
  };
  status: number;
  body: unknown;
  text: string;
};

const parseResponse = async (
  rawResponse: NodeFetchResponse,
  requestMethod: HTTPMethod,
): Promise<ParsedResponse> => {
  const isJson = rawResponse.headers.get('content-type')?.includes('json');
  const req = {
    path: rawResponse.url,
    method: requestMethod,
  };
  const { status } = rawResponse;
  if (isJson) {
    const body = await rawResponse.json();
    const text = JSON.stringify(body);
    return {
      req,
      status,
      body,
      text,
    };
  }
  const text = await rawResponse.text();
  return {
    req,
    status,
    body: {},
    text,
  };
};

describe('test', () => {
  it('passes', async () => {
    const rawResponse = await fetch('endpoint');
    const res = await parseResponse(rawResponse, 'GET');
    expect(res).to.satisfyApiSpec;
  });
});

Longer term solution
A new async assertion?

describe('test', () => {
  it('passes', async () => {
    const method = 'GET';
	const res = await fetch('endpoint', { method });
    await expect(res).toEventuallySatisfyApiSpec(method);
  });
});

Or, expose the above parseResponse helper function as parseNodeFetchResponse.

[rmclaughlin-nelnet]

Thanks for looking into it. the first solution should be good enough for me, but I agree a longer term solution would be better. I was trying out the first solution, but I ran into problems. Here is what I did, slightly different from what you typed out.

const rawResponse = await fetch('endpoint');
    const body = await rawResponse.json();
    const res = {
      req: {
        path: rawResponse.url,
        method: 'POST',
      },
      body,
      text: JSON.stringify(body),
    };
    expect(res).toSatisfyApiSpec();

TypeError: Cannot read property '_json' of undefined

       98 |       text: JSON.stringify(body),
       99 |     };
    > 100 |     expect(res).toSatisfyApiSpec();
          |                 ^
      101 |   });
      102 | });
      103 |

[rwalle61]

Ah, sorry I miswrote the first solution slightly, you need the status field so that we parse the response as a SuperAgent response, rather than a RequestPromise response (hence why it expected _json)

I've corrected the above example, so it should work when a response header specifies the content type is json.

If instead the content type is text, use this:

describe('test', () => {
  it('passes', async () => {
    const rawResponse = await fetch('endpoint');
    const text = await rawResponse.text();
    const res = {
      req: {
        path: rawResponse.url,
        method: 'GET',
      },
      status: rawResponse.status,
      body: {},
      text,
    };
    expect(res).to.satisfyApiSpec;
  });
});

Let me know if these work, and we can find a better long-term solution

[rmclaughlin-nelnet]

Ok, I got it to work with a few tweaks

const rawResponse = await fetch('endpoint');
const body = await rawResponse.json();
const res = {
  req: {
    path: rawResponse.url,
    method: 'GET',
  },
  status: rawResponse.status,
  body,
};
expect(res).toSatisfyApiSpec();

1. It looks like body is the correct property to fill in, not text
2. You were using expect(res).to.satisfyApiSpec; but I had to use expect(res).toSatisfyApiSpec();
3. It looks like it does not validate that a property does or does not exist, only that, if it exists, it is the correct type, is that correct? I tried breaking the test by removing/changing the names of properties in the swagger file, but the test kept passing. It was only when I changed the type (from string to number) that I was able to get the test to fail.

[rwalle61]

Thanks! In answer to your points:

1. ah yes I think adding text is unnecessary
2. good spot, my example was for the chai plugin, whereas you're using jest.
3. would you mind pasting the relevant part of your swagger file? To fail tests by removing/changing the names of properties in the swagger file, I think your response schema should have additionalProperties: false and/or required properties