feature: @putout/printer: type-checker: improve handling of absent arrow

Author: coderaiser

lib/tokenize/expressions/array-expression/comma.js

@@ -30,8 +30,8 @@ export const isNewlineAfterComma = createTypeChecker([
 
 const isSimpleBetweenObjects = createTypeChecker([
     ['+', callWithNext(isObjectExpression)],
-    ['-: SpreadElement'],
-    ['-: Identifier'],
+    ['-: -> SpreadElement'],
+    ['-: -> Identifier'],
     ['+: -> !CallExpression'],
 ]);
 

lib/tokenize/expressions/binary-expression/is-concatenation.js

@@ -6,7 +6,7 @@ export const isConcatenation = createTypeChecker([
     ['-: parentPath -> ReturnStatement'],
     ['-: node.operator -> !', isPlus],
     ['-: node.loc', isSameLine],
-    ['+: BinaryExpression'],
+    ['+: -> BinaryExpression'],
 ]);
 
 function isSameLine(loc) {

lib/tokenize/type-checker/type-checker.js

@@ -3,6 +3,8 @@ import {instrument as _instrument} from '#type-checker/instrument';
 import {parseOperation, parseTypeNames} from './parsers.js';
 import {equal, maybeCall} from './comparators.js';
 
+const isString = (a) => typeof a === 'string';
+
 const SKIP = [
     Infinity,
     false,
@@ -29,6 +31,7 @@ export const createTypeChecker = (typeNames, overrides = {}) => {
     }
 
     validateResults(results);
+    validateTypeNames(checkers);
 
     const typeChecker = (path, options) => {
         for (const [index, {result, selector, typeName, not}] of checkers.entries()) {
@@ -54,3 +57,12 @@ function validateResults(results) {
     if (!results.has(true))
         throw Error(`☝️Looks like type checker missing successful route ('+'), it will always fail`);
 }
+
+const hasTypeName = ({typeName}) => isString(typeName);
+
+function validateTypeNames(checkers) {
+    for (const {typeName} of checkers.filter(hasTypeName)) {
+        if (typeName.includes(':'))
+            throw Error(`☝️Looks like typeName includes ':', most likely you forget the arrow: ' -> '`);
+    }
+}

lib/tokenize/type-checker/type-checker.spec.js

@@ -501,3 +501,14 @@ test('printer: type-checker: isFunction: cut options', (t) => {
     t.ok(result);
     t.end();
 });
+
+test('printer: type-checker: no arrow', (t) => {
+    const [error] = tryCatch(createTypeChecker, [
+        '+: ClassDeclaration',
+    ]);
+    
+    const expected = `☝️Looks like typeName includes ':', most likely you forget the arrow: ' -> '`;
+    
+    t.equal(error.message, expected);
+    t.end();
+});