fix(writeFile): preserve file mode when saving files (#33)

Author: billiegoose

src/CacheFS.js

@@ -164,7 +164,7 @@ module.exports = class CacheFS {
     let ino;
     try {
       let oldStat = this.stat(filepath);
-      if (mode === null) {
+      if (mode == null) {
         mode = oldStat.mode;
       }
       ino = oldStat.ino;

src/__tests__/fs.promises.spec.js

@@ -69,6 +69,22 @@ describe("fs.promises module", () => {
         });
       });
     });
+    it("write file perserves old mode", done => {
+      fs.mkdir("/writeFile").finally(() => {
+        fs.writeFile("/writeFile/writeFile-mode.txt", "HELLO", { mode: 0o635 }).then(() => {
+          fs.stat("/writeFile/writeFile-mode.txt").then(stats => {
+            let mode = stats.mode;
+            expect(mode).toEqual(0o635)
+            fs.writeFile("/writeFile/writeFile-mode.txt", "WORLD").then(() => {
+              fs.stat("/writeFile/writeFile-mode.txt").then(stats => {
+                expect(stats.mode).toEqual(0o635);
+                done();
+              });
+            });
+          });
+        });
+      });
+    });
   });
 
   describe("readFile", () => {