feat(eslint-plugin): [no-floating-promises] add suggestion fixer to add an 'await'

packages/eslint-plugin/src/rules/no-floating-promises.ts

@@ -12,7 +12,11 @@ type Options = [
   },
 ];
 
-type MessageId = 'floating' | 'floatingVoid' | 'floatingFixVoid';
+type MessageId =
+  | 'floating'
+  | 'floatingVoid'
+  | 'floatingFixVoid'
+  | 'floatingFixAwait';
 
 export default util.createRule<Options, MessageId>({
   name: 'no-floating-promises',
@@ -27,6 +31,7 @@ export default util.createRule<Options, MessageId>({
     messages: {
       floating:
         'Promises must be awaited, end with a call to .catch, or end with a call to .then with a rejection handler.',
+      floatingFixAwait: 'Add await operator.',
       floatingVoid:
         'Promises must be awaited, end with a call to .catch, end with a call to .then with a rejection handler' +
         ' or be explicitly marked as ignored with the `void` operator.',
@@ -95,6 +100,23 @@ export default util.createRule<Options, MessageId>({
             context.report({
               node,
               messageId: 'floating',
+              suggest: [
+                {
+                  messageId: 'floatingFixAwait',
+                  fix(fixer): TSESLint.RuleFix {
+                    if (
+                      expression.type === AST_NODE_TYPES.UnaryExpression &&
+                      expression.operator === 'void'
+                    ) {
+                      return fixer.replaceTextRange(
+                        [expression.range[0], expression.range[0] + 4],
+                        'await',
+                      );
+                    }
+                    return fixer.insertTextBefore(node, 'await ');
+                  },
+                },
+              ],
             });
           }
         }

packages/eslint-plugin/tests/rules/no-floating-promises.test.ts

@@ -656,6 +656,68 @@ async function test() {
         {
           line: 3,
           messageId: 'floating',
+          suggestions: [
+            {
+              messageId: 'floatingFixAwait',
+              output: `
+async function test() {
+  await Promise.resolve();
+}
+      `,
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+async function test() {
+  const promise = new Promise((resolve, reject) => resolve('value'));
+  promise;
+}
+      `,
+      options: [{ ignoreVoid: false }],
+      errors: [
+        {
+          line: 4,
+          messageId: 'floating',
+          suggestions: [
+            {
+              messageId: 'floatingFixAwait',
+              output: `
+async function test() {
+  const promise = new Promise((resolve, reject) => resolve('value'));
+  await promise;
+}
+      `,
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+async function returnsPromise() {
+  return 'value';
+}
+void returnsPromise();
+      `,
+      options: [{ ignoreVoid: false }],
+      errors: [
+        {
+          line: 5,
+          messageId: 'floating',
+          suggestions: [
+            {
+              messageId: 'floatingFixAwait',
+              output: `
+async function returnsPromise() {
+  return 'value';
+}
+await returnsPromise();
+      `,
+            },
+          ],
         },
       ],
     },