[find-and-replace] Ensure a pattern without any path separators… (#1544)

* [find-and-replace] Ensure a pattern without any path separators…

…will be applied against only the filename rather than the entire path.

For example: `*.js` should search all JavaScript files, not just the ones at the project root.

* (Forgot about negated patterns!)

* Fix comment

* (I thought I removed this)

Author: savetheclocktower

spec/workspace-spec.js

@@ -2279,6 +2279,20 @@ describe('Workspace', () => {
         atom.workspace.filePathMatchesPatterns(pathB1, ['!b-dir/*.js'])
       ).toBe(false);
 
+      expect(
+        atom.workspace.filePathMatchesPatterns(pathA1, ['*.js'])
+      ).toBe(true);
+      expect(
+        atom.workspace.filePathMatchesPatterns(pathB1, ['*.js'])
+      ).toBe(true);
+
+      expect(
+        atom.workspace.filePathMatchesPatterns(pathA1, ['!*.js'])
+      ).toBe(false);
+      expect(
+        atom.workspace.filePathMatchesPatterns(pathB1, ['!*.js'])
+      ).toBe(false);
+
       expect(
         atom.workspace.filePathMatchesPatterns(pathA1, positiveGlobs)
       ).toBe(false);

src/workspace.js

@@ -42,15 +42,33 @@ function filePathMatchesGlob(filePath, matcher) {
   return matcher.negate ? true : false;
 }
 
-// Trim trailing path separators from the ends of patterns. This makes it so
-// that `foo/` and `foo` are treated identically.
+// Transform a pattern prior to handing it off to `minimatch`.
 function normalizePattern (rawPath) {
+  // Strip any trailing path separator.
   // The path separator is `\` on Windows, but we also allow usage of `/`;
   // hence we check for both here.
   if (rawPath.endsWith(path.sep) || rawPath.endsWith('/')) {
-    return rawPath.substring(0, rawPath.length - 1);
+    rawPath = rawPath.substring(0, rawPath.length - 1);
   }
-  return rawPath;
+
+  // Keep any path negation separate from the rest, since it needs to stay at
+  // the beginning no matter what.
+  let negation = '';
+  if (rawPath.startsWith('!')) {
+    rawPath = rawPath.slice(1);
+    negation = '!';
+  }
+
+  // If a user searches for (e.g.) `*.js`, we want to search all `.js` files
+  // anywhere in the project, not just in the root. That means we should treat
+  // patterns as implicitly prepending `**/` if they contain no path separators.
+  //
+  // NOTE: This is stricter than VS Code's approach, which is to prepend `**/`
+  // to _all_ patterns unless the user specifically opts out by starting a
+  // path with `/`. This would make plenty of sense for us, but would be a
+  // change in behavior, so for now we're going with this as a compromise.
+  let prefix = (rawPath.includes(path.sep) || rawPath.includes('/')) ? '' : `**${path.sep}`;
+  return `${negation}${prefix}${rawPath}`;
 }
 
 // Given a path pattern like `foo/bar/baz` and a list of the current root path