fix(prefer-snapshot-hint): support passing hint to toMatchSnapshot …

…as first argument (#1070)

src/rules/__tests__/prefer-snapshot-hint.test.ts

@@ -28,6 +28,28 @@ ruleTester.run('prefer-snapshot-hint (always)', rule, {
       code: 'expect(1).toMatchSnapshot({}, "my snapshot");',
       options: ['always'],
     },
+    {
+      code: 'expect(1).toMatchSnapshot("my snapshot");',
+      options: ['always'],
+    },
+    {
+      code: 'expect(1).toMatchSnapshot(`my snapshot`);',
+      options: ['always'],
+    },
+    {
+      code: dedent`
+        const x = {};
+        expect(1).toMatchSnapshot(x, "my snapshot");
+      `,
+      options: ['always'],
+    },
+    {
+      code: dedent`
+        const x = "snapshot";
+        expect(1).toMatchSnapshot(\`my $\{x}\`);
+      `,
+      options: ['always'],
+    },
     {
       code: 'expect(1).toThrowErrorMatchingSnapshot("my snapshot");',
       options: ['always'],
@@ -64,6 +86,20 @@ ruleTester.run('prefer-snapshot-hint (always)', rule, {
         },
       ],
     },
+    {
+      code: dedent`
+        const x = "we can't know if this is a string or not"; 
+        expect(1).toMatchSnapshot(x);
+      `,
+      options: ['always'],
+      errors: [
+        {
+          messageId: 'missingHint',
+          column: 11,
+          line: 2,
+        },
+      ],
+    },
     {
       code: 'expect(1).toThrowErrorMatchingSnapshot();',
       options: ['always'],

src/rules/prefer-snapshot-hint.ts

@@ -2,6 +2,7 @@ import {
   ParsedExpectMatcher,
   createRule,
   isExpectCall,
+  isStringNode,
   parseExpectCall,
 } from './utils';
 
@@ -12,10 +13,27 @@ const isSnapshotMatcher = (matcher: ParsedExpectMatcher) => {
 };
 
 const isSnapshotMatcherWithoutHint = (matcher: ParsedExpectMatcher) => {
-  const expectedNumberOfArgumentsWithHint =
-    1 + Number(matcher.name === 'toMatchSnapshot');
-
-  return matcher.arguments?.length !== expectedNumberOfArgumentsWithHint;
+  if (!matcher.arguments || matcher.arguments.length === 0) {
+    return true;
+  }
+
+  // this matcher only supports one argument which is the hint
+  if (matcher.name !== 'toMatchSnapshot') {
+    return matcher.arguments.length !== 1;
+  }
+
+  // if we're being passed two arguments,
+  // the second one should be the hint
+  if (matcher.arguments.length === 2) {
+    return false;
+  }
+
+  const [arg] = matcher.arguments;
+
+  // the first argument to `toMatchSnapshot` can be _either_ a snapshot hint or
+  // an object with asymmetric matchers, so we can't just assume that the first
+  // argument is a hint when it's by itself.
+  return !isStringNode(arg);
 };
 
 const messages = {