Fix: Ignore hidden folders when resolving globs (fixes #8259) (#8270)

This is a performance improvement, but should not be a change to linting
functionality.  This is similar to avoiding glob resolution within
`node_modules`.  With this change, `node-glob` will not attempt to 
find all files within `.dotfolder` folders.  Similar to `node_modules`,
this can be overridden in a user’s ignore file or in an ignore-pattern.

lib/ignored-paths.js

@@ -201,6 +201,12 @@ class IgnoredPaths {
 
         const ig = ignore().add(DEFAULT_IGNORE_DIRS);
 
+        if (this.options.dotfiles !== true) {
+
+            // Ignore hidden folders.  (This cannot be ".*", or else it's not possible to unignore hidden files)
+            ig.add([".*/*", "!../"]);
+        }
+
         if (this.options.ignore) {
             ig.add(this.ig.custom);
         }

tests/fixtures/ignored-paths/.eslintignoreWithUnignoredDefaults

@@ -1,2 +1,3 @@
 !/node_modules/package
 !/bower_components/package
+!.hidden/package

tests/lib/ignored-paths.js

@@ -550,9 +550,10 @@ describe("IgnoredPaths", () => {
             assert.isTrue(shouldIgnore(resolve("bower_components/a")));
             assert.isTrue(shouldIgnore(resolve("bower_components/a/b")));
             assert.isFalse(shouldIgnore(resolve(".hidden")));
+            assert.isTrue(shouldIgnore(resolve(".hidden/a")));
         });
 
-        it("should ignore default folders there is an ignore file without unignored defaults", () => {
+        it("should ignore default folders when there is an ignore file without unignored defaults", () => {
             const cwd = getFixturePath();
             const ignoredPaths = new IgnoredPaths({ ignore: true, ignorePath: getFixturePath(".eslintignore"), cwd });
 
@@ -564,6 +565,7 @@ describe("IgnoredPaths", () => {
             assert.isTrue(shouldIgnore(resolve("bower_components/a")));
             assert.isTrue(shouldIgnore(resolve("bower_components/a/b")));
             assert.isFalse(shouldIgnore(resolve(".hidden")));
+            assert.isTrue(shouldIgnore(resolve(".hidden/a")));
         });
 
         it("should not ignore things which are re-included in ignore file", () => {
@@ -578,8 +580,10 @@ describe("IgnoredPaths", () => {
             assert.isTrue(shouldIgnore(resolve("bower_components/a")));
             assert.isTrue(shouldIgnore(resolve("bower_components/a/b")));
             assert.isFalse(shouldIgnore(resolve(".hidden")));
+            assert.isTrue(shouldIgnore(resolve(".hidden/a")));
             assert.isFalse(shouldIgnore(resolve("node_modules/package")));
             assert.isFalse(shouldIgnore(resolve("bower_components/package")));
+            assert.isFalse(shouldIgnore(resolve(".hidden/package")));
         });
 
         it("should ignore files which we try to re-include in ignore file when ignore option is disabled", () => {
@@ -594,8 +598,10 @@ describe("IgnoredPaths", () => {
             assert.isTrue(shouldIgnore(resolve("bower_components/a")));
             assert.isTrue(shouldIgnore(resolve("bower_components/a/b")));
             assert.isFalse(shouldIgnore(resolve(".hidden")));
+            assert.isTrue(shouldIgnore(resolve(".hidden/a")));
             assert.isTrue(shouldIgnore(resolve("node_modules/package")));
             assert.isTrue(shouldIgnore(resolve("bower_components/package")));
+            assert.isTrue(shouldIgnore(resolve(".hidden/package")));
         });
 
         it("should not ignore dirs which are re-included by ignorePattern", () => {
@@ -610,9 +616,21 @@ describe("IgnoredPaths", () => {
             assert.isTrue(shouldIgnore(resolve("bower_components/a")));
             assert.isTrue(shouldIgnore(resolve("bower_components/a/b")));
             assert.isFalse(shouldIgnore(resolve(".hidden")));
+            assert.isTrue(shouldIgnore(resolve(".hidden/a")));
             assert.isFalse(shouldIgnore(resolve("node_modules/package")));
             assert.isTrue(shouldIgnore(resolve("bower_components/package")));
         });
+
+        it("should not ignore hidden dirs when dotfiles is enabled", () => {
+            const cwd = getFixturePath("no-ignore-file");
+            const ignoredPaths = new IgnoredPaths({ ignore: true, cwd, dotfiles: true });
+
+            const shouldIgnore = ignoredPaths.getIgnoredFoldersGlobChecker();
+            const resolve = createResolve(cwd);
+
+            assert.isFalse(shouldIgnore(resolve(".hidden")));
+            assert.isFalse(shouldIgnore(resolve(".hidden/a")));
+        });
     });
 
 });