Type observables based on how they're consumed by AVA

Detect subscribables and convert to promise. Simplify type description to match what AVA actually requires.

Co-authored-by: Mark Wubben <[email protected]>

Author: micaelmbagira

index.d.ts

@@ -1,8 +1,10 @@
 /// <reference types="node"/>
 
-export interface ObservableLike {
-	subscribe(observer: (value: unknown) => void): void;
-	[Symbol.observable](): ObservableLike;
+export interface Subscribable {
+	subscribe(observer: {
+		error(err: any): void,
+		complete(): void,
+	}): void
 }
 
 export type Constructor = (new (...args: Array<any>) => any);
@@ -472,7 +474,7 @@ export interface CbExecutionContext<Context = unknown> extends ExecutionContext<
 	end(error?: any): void;
 }
 
-export type ImplementationResult = PromiseLike<void> | ObservableLike | void;
+export type ImplementationResult = PromiseLike<void> | Subscribable | void;
 export type Implementation<Context = unknown> = (t: ExecutionContext<Context>) => ImplementationResult;
 export type CbImplementation<Context = unknown> = (t: CbExecutionContext<Context>) => ImplementationResult;
 

lib/test.js

@@ -1,8 +1,6 @@
 'use strict';
 const concordance = require('concordance');
-const observableToPromise = require('observable-to-promise');
 const isPromise = require('is-promise');
-const isObservable = require('is-observable');
 const plur = require('plur');
 const assert = require('./assert');
 const nowAndTimers = require('./now-and-timers');
@@ -577,12 +575,17 @@ class Test {
 			return this.finishPromised();
 		}
 
-		const returnedObservable = isObservable(result.retval);
+		const returnedObservable = result.retval !== null && typeof result.retval === 'object' && typeof result.retval.subscribe === 'function';
 		const returnedPromise = isPromise(result.retval);
 
 		let promise;
 		if (returnedObservable) {
-			promise = observableToPromise(result.retval);
+			promise = new Promise((resolve, reject) => {
+				result.retval.subscribe({
+					error: reject,
+					complete: () => resolve()
+				});
+			});
 		} else if (returnedPromise) {
 			// `retval` can be any thenable, so convert to a proper promise.
 			promise = Promise.resolve(result.retval);

package-lock.json

@@ -85,15 +85,13 @@
 		"indent-string": "^4.0.0",
 		"is-ci": "^2.0.0",
 		"is-error": "^2.2.2",
-		"is-observable": "^2.0.0",
 		"is-plain-object": "^3.0.0",
 		"is-promise": "^2.1.0",
 		"lodash": "^4.17.15",
 		"matcher": "^2.1.0",
 		"md5-hex": "^3.0.1",
 		"micromatch": "^4.0.2",
 		"ms": "^2.1.2",
-		"observable-to-promise": "^1.0.0",
 		"ora": "^4.0.3",
 		"p-map": "^3.0.0",
 		"pkg-conf": "^3.1.0",