Accepting generic type for table definition (#42011)

types/cucumber/cucumber-tests.ts

@@ -1,9 +1,20 @@
 import * as assert from "power-assert";
-import { setDefinitionFunctionWrapper, setWorldConstructor, defineParameterType, After, AfterAll, Before, BeforeAll, Given, When, Then } from "cucumber";
+import {
+    setDefinitionFunctionWrapper,
+    setWorldConstructor,
+    defineParameterType,
+    After,
+    AfterAll,
+    Before,
+    BeforeAll,
+    Given,
+    When,
+    Then,
+    TableDefinition as Table
+} from "cucumber";
 import cucumber = require("cucumber");
 
 type Callback = cucumber.CallbackStepDefinition;
-type Table = cucumber.TableDefinition;
 type HookScenarioResult = cucumber.HookScenarioResult;
 const Status = cucumber.Status;
 
@@ -159,6 +170,24 @@ function StepSampleWithoutDefineSupportCode() {
         assert.deepEqual(actual, expected);
     });
 
+    interface MyTableType {
+        Vegetable: string;
+        Rating: string;
+    }
+
+    Given(/^a table step with a Type$/, (table: Table<MyTableType>) => {
+        const expected = [
+            { Vegetable: 'Apricot', Rating: '5' },
+            { Vegetable: 'Brocolli', Rating: '2' },
+            { Vegetable: 'Cucumber', Rating: '10' }
+        ];
+        const [actual] = table.hashes();
+        assert.deepEqual(actual.Vegetable, 'Apricot');
+        assert.deepEqual(actual.Rating, '5');
+
+        assert.deepEqual(actual.WrongField, '5'); // $ExpectError
+    });
+
     defineParameterType({
         regexp: /particular/,
         transformer: s => s.toUpperCase(),

types/cucumber/index.d.ts

@@ -8,6 +8,7 @@
 //                 Peter Morlion <https://github.com/petermorlion>
 //                 Don Jayamanne <https://github.com/DonJayamanne>
 //                 David Goss <https://github.com/davidjgoss>
+//                 Alberto Silva <https://github.com/albertossilva>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.4
 
@@ -29,7 +30,7 @@ export interface CallbackStepDefinition {
     (error?: any, pending?: string): void;
 }
 
-export interface TableDefinition {
+export interface TableDefinition<Type = any> {
     /** Returns the table as a 2-D array. */
     raw(): string[][];
 
@@ -37,10 +38,10 @@ export interface TableDefinition {
     rows(): string[][];
 
     /** Returns an object where each row corresponds to an entry (first column is the key, second column is the value). */
-    rowsHash(): { [firstCol: string]: string };
+    rowsHash(): { [firstColumn: string]: string };
 
     /** Returns an array of objects where each row is converted to an object (column header is the key). */
-    hashes(): Array<{ [colName: string]: string }>;
+    hashes(): Array<{ [columnName in keyof Type]: string }>;
 }
 
 export type StepDefinitionCode = (this: World, ...stepArgs: any[]) => any;