Rename regexp variables in findMatchingFiles.js

There was some confusion around these variables, so I made it clearer
what is a compiled regexp and what is just a string pattern.

Before making the rename, I went down the path of switching to passing
in a compiled RegExp to all places. But I couldn't get
the `egrep` call inside `findMatchingFilesWithFind` to work with the
`toString()` output of RegExp. So I decided to keep the string
throughout all finders (so that it's consistent).

lib/findMatchingFiles.js

@@ -10,14 +10,14 @@ import normalizePath from './normalizePath';
 
 function findMatchingFilesWithFind(
   lookupPath: string,
-  validFilesRegex: string
+  validFilesPattern: string
 ): Promise<Array<string>> {
   const findCommand = [
     `find ${lookupPath}`,
     '-name "**.js*"',
     '-not -path "./node_modules/*"',
   ].join(' ');
-  const command = `${findCommand} | egrep -i \"${validFilesRegex}\"`;
+  const command = `${findCommand} | egrep -i \"${validFilesPattern}\"`;
 
   return new Promise((resolve: Function, reject: Function) => {
     // TODO switch to spawn so we can start processing the stream as it comes
@@ -36,8 +36,9 @@ function findMatchingFilesWithFind(
 
 function findMatchingFilesWithNode(
   lookupPath: string,
-  validFilesRegex: string
+  validFilesPattern: string
 ): Promise<Array<string>> {
+  const validFilesRegex = new RegExp(validFilesPattern, 'i');
   return new Promise((resolve: Function, reject: Function) => {
     glob(`${lookupPath}/**/*.js*`, {
       ignore: './node_modules/**',
@@ -47,16 +48,16 @@ function findMatchingFilesWithNode(
         return;
       }
       resolve(result.filter((filePath: string): bool =>
-        new RegExp(validFilesRegex, 'i').test(filePath)));
+        validFilesRegex.test(filePath)));
     });
   });
 }
 
 function findMatchingFilesWithWatchman(
   lookupPath: string,
-  validFilesRegex: string
+  validFilesPattern: string
 ): Promise<Array<string>> {
-  const tester = new RegExp(validFilesRegex, 'i');
+  const validFilesRegex = new RegExp(validFilesPattern, 'i');
   const normalizedLookupPath = normalizePath(lookupPath);
   return new Promise((resolve: Function) => {
     const matches = [];
@@ -65,7 +66,7 @@ function findMatchingFilesWithWatchman(
       if (!filePath.startsWith(normalizedLookupPath)) {
         return;
       }
-      if (tester.test(filePath)) {
+      if (validFilesRegex.test(filePath)) {
         matches.push(filePath);
       }
     });
@@ -87,14 +88,14 @@ export default function findMatchingFiles(
   }
 
   const formattedVarName = formattedToRegex(variableName);
-  const validFilesRegex = `(/|^)${formattedVarName}(/index)?(/package)?\\.js.*`;
+  const validFilesPattern = `(/|^)${formattedVarName}(/index)?(/package)?\\.js.*`;
 
   if (WatchmanFileCache.isEnabled()) {
-    return findMatchingFilesWithWatchman(lookupPath, validFilesRegex);
+    return findMatchingFilesWithWatchman(lookupPath, validFilesPattern);
   }
   if (/^win/.test(process.platform) ||
       process.env.IMPORT_JS_USE_NODE_FINDER) {
-    return findMatchingFilesWithNode(lookupPath, validFilesRegex);
+    return findMatchingFilesWithNode(lookupPath, validFilesPattern);
   }
-  return findMatchingFilesWithFind(lookupPath, validFilesRegex);
+  return findMatchingFilesWithFind(lookupPath, validFilesPattern);
 }