feat: add du method (#45)

Author: billiegoose

src/CacheFS.js

@@ -248,4 +248,19 @@ module.exports = class CacheFS {
     dir.set(basename, entry);
     return stat;
   }
+  _du (dir) {
+    let size = 0;
+    for (const [name, entry] of dir.entries()) {
+      if (name === STAT) {
+        size += entry.size;
+      } else {
+        size += this._du(entry);
+      }
+    }
+    return size;
+  }
+  du (filepath) {
+    let dir = this._lookup(filepath);
+    return this._du(dir);
+  }
 };

src/PromisifiedFS.js

@@ -48,6 +48,7 @@ module.exports = class PromisifiedFS {
     this.readlink = this._wrap(this.readlink, false)
     this.symlink = this._wrap(this.symlink, true)
     this.backFile = this._wrap(this.backFile, true)
+    this.du = this._wrap(this.du, false);
 
     this.saveSuperblock = debounce(() => {
       this._saveSuperblock();
@@ -303,4 +304,7 @@ module.exports = class PromisifiedFS {
     await this._writeStat(filepath, size, opts)
     return null
   }
+  async du(filepath) {
+    return this._cache.du(filepath);
+  }
 }

src/__tests__/fs.promises.spec.js

@@ -446,4 +446,31 @@ describe("fs.promises module", () => {
     });
   });
 
+  describe("du", () => {
+    it("du returns the total file size of a path", done => {
+      fs.mkdir("/du").finally(() => {
+        fs.writeFile("/du/a.txt", "hello").then(() => {
+          fs.writeFile("/du/b.txt", "hello").then(() => {
+            fs.mkdir("/du/sub").then(() => {
+              fs.writeFile("/du/sub/a.txt", "hello").then(() => {
+                fs.writeFile("/du/sub/b.txt", "hello").then(() => {
+                  fs.du("/du/sub/a.txt").then(size => {
+                    expect(size).toBe(5)
+                    fs.du("/du/sub").then(size => {
+                      expect(size).toBe(10)
+                      fs.du("/du").then(size => {
+                        expect(size).toBe(20)
+                        done();
+                      });
+                    });
+                  });
+                });
+              });
+            });
+          });
+        });
+      });
+    });
+  });
+
 });