fix: handling of nested unignores (#119)

The fix in #116 was not quite complete. git does allow unignoring
directories as long as its path to the root is unignored. This modifies
the check to handle this case. The test case in `nested-ignores.js` was
indeed wrong because it interpreted unignoring a specific file
`!/h/c/d/hcd` as unignoring the directory `!/h/c/d`. I added new tests
that specifically unignore a directory and therefore allow unignoring
anything else within it.

## References
Related to #116

lib/index.js

@@ -22,6 +22,7 @@ class Walker extends EE {
     this.result = this.parent ? this.parent.result : new Set()
     this.entries = null
     this.sawError = false
+    this.exact = opts.exact
   }
 
   sort (a, b) {
@@ -164,7 +165,7 @@ class Walker extends EE {
     } else {
       // is a directory
       if (dir) {
-        this.walker(entry, { isSymbolicLink }, then)
+        this.walker(entry, { isSymbolicLink, exact: file || this.filterEntry(entry + '/') }, then)
       } else {
         then()
       }
@@ -218,7 +219,7 @@ class Walker extends EE {
       const parentEntry = this.basename + '/' + entry
       const parentBasename = entryBasename || entry
       included = this.parent.filterEntry(parentEntry, partial, parentBasename)
-      if (!included && partial) {
+      if (!included && !this.exact) {
         return false
       }
     }

test/nested-ignores.js

@@ -26,9 +26,6 @@ var expected = [
   'c/d/c/ccc',
   'c/d/d/ccc',
   'd/c/h/.dch',
-  'h/c/d/.hcd',
-  'h/c/d/dch',
-  'h/c/d/ddd',
   'h/c/d/hcd',
 ]
 

test/preserve-ignores.js → test/nested-unignores.js

@@ -7,12 +7,25 @@ const path = resolve(__dirname, 'fixtures')
 // set the ignores just for this test
 var c = require('./common.js')
 c.ignores({
-  '.ignore': ['*', '!/c', '!/d'],
+  '.ignore': ['*', '!/c/d', '!/d/c', '!/d/d/', '!/d/h/h'],
   'c/.ignore': ['!*', '.ignore'], // unignore everything
+  'd/c/.ignore': ['!h', '!cc*'], // unignore directory
+  'd/d/.ignore': ['!h/', '!cc*'], // unignore directory with slash
+  'd/h/h/.ignore': ['!dd*'], // unignore files
 })
 
 // the only files we expect to see
-var expected = []
+var expected = [
+  'd/c/h/ccc',
+  'd/c/h/ccd',
+  'd/c/h/cch',
+  'd/d/h/ccc',
+  'd/d/h/ccd',
+  'd/d/h/cch',
+  'd/h/h/ddc',
+  'd/h/h/ddd',
+  'd/h/h/ddh',
+]
 
 const t = require('tap')