feature: @putout/plugin-typescript: apply-type-guards: function

Author: coderaiser

packages/plugin-typescript/lib/apply-type-guards/fixture/fn-fix.ts

@@ -0,0 +1 @@
+const isFn = (a): a is Function => typeof a === 'function';

packages/plugin-typescript/lib/apply-type-guards/fixture/fn.ts

@@ -0,0 +1 @@
+const isFn = (a) => typeof a === 'function'

packages/plugin-typescript/lib/apply-type-guards/index.js

@@ -4,8 +4,8 @@ import {
     template,
 } from 'putout';
 
-const {replaceWith} = operator;
 const {identifier} = types;
+const {replaceWith} = operator;
 
 const create = template('(__a): __a is __c => typeof __a === "__b"', {
     placeholderPattern: /__/,
@@ -19,12 +19,21 @@ export const match = () => ({
 
 export const replace = () => ({
     '(__a) => typeof __a === "__b"': ({__a, __b}, path) => {
+        const __c = parseGuard(__b);
+        
         replaceWith(path, create({
             __a,
             __b,
-            __c: identifier(__b.value),
+            __c,
         }));
 
         return path;
     },
 });
+
+function parseGuard({value}) {
+    if (value === 'function')
+        return identifier('Function');
+    
+    return identifier(value);
+}

packages/plugin-typescript/lib/apply-type-guards/index.spec.js

@@ -21,3 +21,8 @@ test('plugin-apply-guards: no report: exists', (t) => {
     t.noReport('exists');
     t.end();
 });
+
+test('plugin-apply-guards: transform: fn', (t) => {
+    t.transform('fn');
+    t.end();
+});