Treat a leading "!" in a bracket expression as negation by default

lib/parse.js

@@ -748,7 +748,7 @@ const parse = (input, options) => {
         value = `\\${value}`;
       }
 
-      if (opts.posix === true && value === '!' && prev.value === '[') {
+      if (value === '!' && prev.value === '[') {
         value = '^';
       }
 

test/brackets.js

@@ -23,4 +23,44 @@ describe('brackets', () => {
       assert(!isMatch('a/b', '[a]*'));
     });
   });
+  describe('negation with "!"', () => {
+    it('should negate a bracket expression with a leading "!"', () => {
+      assert(!isMatch('a', '[!abc]'));
+      assert(!isMatch('b', '[!abc]'));
+      assert(!isMatch('c', '[!abc]'));
+      assert(isMatch('d', '[!abc]'));
+      assert(isMatch('x', '[!abc]'));
+    });
+
+    it('should negate ranges with a leading "!"', () => {
+      assert(!isMatch('a', '[!a-c]'));
+      assert(!isMatch('c', '[!a-c]'));
+      assert(isMatch('d', '[!a-c]'));
+    });
+
+    it('should agree with "^" negation', () => {
+      assert.strictEqual(isMatch('a', '[!abc]'), isMatch('a', '[^abc]'));
+      assert.strictEqual(isMatch('d', '[!abc]'), isMatch('d', '[^abc]'));
+      assert.strictEqual(isMatch('a', '[!a-c]'), isMatch('a', '[^a-c]'));
+      assert.strictEqual(isMatch('d', '[!a-c]'), isMatch('d', '[^a-c]'));
+    });
+
+    it('should negate within a larger pattern', () => {
+      assert(!isMatch('abc', 'a[!b]c'));
+      assert(isMatch('axc', 'a[!b]c'));
+      assert(!isMatch('ad', '[!abc]d'));
+      assert(isMatch('xd', '[!abc]d'));
+    });
+
+    it('should treat "!" as a literal when it is not leading', () => {
+      assert(isMatch('!', '[a!]'));
+      assert(isMatch('a', '[a!]'));
+      assert(!isMatch('b', '[a!]'));
+    });
+
+    it('should negate a literal "!"', () => {
+      assert(!isMatch('!', '[!!]'));
+      assert(isMatch('a', '[!!]'));
+    });
+  });
 });