Don't throw an error in case where only one of host or port are defines

Author: dlarocque

packages/rules-unit-testing/src/impl/discovery.ts

@@ -88,25 +88,16 @@ export function getEmulatorHostAndPort(
   discovered?: DiscoveredEmulators
 ) {
   if (conf && 'host' in conf && 'port' in conf) {
-    const { host, port } = conf;
-    if (host || port) {
-      if (!host || !port) {
-        throw new Error(
-          `Invalid configuration ${emulator}.host=${host} and ${emulator}.port=${port}. ` +
-            'If either parameter is supplied, both must be defined.'
-        );
-      }
-      if (discovered && !discovered[emulator]) {
-        console.warn(
-          `Warning: config for the ${emulator} emulator is specified, but the Emulator hub ` +
-            'reports it as not running. This may lead to errors such as connection refused.'
-        );
-      }
-      return {
-        host: fixHostname(conf.host, discovered?.hub?.host),
-        port: conf.port
-      };
+    if (discovered && !discovered[emulator]) {
+      console.warn(
+        `Warning: config for the ${emulator} emulator is specified, but the Emulator hub ` +
+          'reports it as not running. This may lead to errors such as connection refused.'
+      );
     }
+    return {
+      host: fixHostname(conf.host, discovered?.hub?.host),
+      port: conf.port
+    };
   }
   const envVar = EMULATOR_HOST_ENV_VARS[emulator];
   const fallback = discovered?.[emulator] || emulatorFromEnvVar(envVar);

packages/rules-unit-testing/test/impl/discovery.test.ts

@@ -123,22 +123,6 @@ describe('getEmulatorHostAndPort()', () => {
       expect(result?.host).to.equal('::1');
     });
 
-    it('throws if only host is present', async () => {
-      expect(() =>
-        getEmulatorHostAndPort('hub', {
-          host: '[::1]'
-        } as HostAndPort)
-      ).to.throw(/hub.port=undefined/);
-    });
-
-    it('throws if only port is present', async () => {
-      expect(() =>
-        getEmulatorHostAndPort('database', {
-          port: 1234
-        } as HostAndPort)
-      ).to.throw(/Invalid configuration database.host=undefined/);
-    });
-
     it('connect to 127.0.0.1 if host is wildcard 0.0.0.0', async () => {
       const result = getEmulatorHostAndPort('hub', {
         host: '0.0.0.0',