Merge pull request #30920 from lukaselmer/feature/improve-superagent-agent

improve superagent.agent() typing

types/superagent/index.d.ts

@@ -6,6 +6,7 @@
 //                 Shrey Jain <https://github.com/shreyjain1994>
 //                 Alec Zopf <https://github.com/zopf>
 //                 Adam Haglund <https://github.com/beeequeue>
+//                 Lukas Elmer <https://github.com/lukaselmer>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.2
 
@@ -45,7 +46,7 @@ declare namespace request {
         // tslint:disable-next-line:unified-signatures
         (method: string, url: string): SuperAgentRequest;
 
-        agent(): SuperAgent<SuperAgentRequest>;
+        agent(): this & Request;
         serialize: { [type: string]: Serializer };
         parse: { [type: string]: Parser };
     }

types/superagent/superagent-tests.ts

@@ -421,3 +421,16 @@ request
     .get('/echo')
     .use(echoPlugin)
     .end();
+
+async function testDefaultOptions() {
+    // Default options for multiple requests
+    const agentWithDefaultOptions = request
+        .agent()
+        .use(() => null)
+        .auth('digest', 'secret', { type: 'auto' });
+
+    await agentWithDefaultOptions.get('/with-plugin-and-auth');
+    await agentWithDefaultOptions.get('/also-with-plugin-and-auth');
+}
+
+testDefaultOptions();