fix: Node polyfill fsAppend rework (#4322)

* My original implementation of `fs.appendFile` used an async API, which, though 
  it would work fine as a polyfill, wasn't an exact match with the Node API.  This PR
  reworks that API to mimic the Node API fully as a synchronous void function with
  an async internal implementation.
* Refactor move of other internal fs `dirent` and `dir` classes to the _fs internal
  directory.

1 files changed, 61 insertions, 48 deletions

diff --git a/std/node/_fs/_fs_appendFile_test.ts b/std/node/_fs/_fs_appendFile_test.ts
index dcea69783..47d552740 100644
--- a/std/node/_fs/_fs_appendFile_test.ts
+++ b/std/node/_fs/_fs_appendFile_test.ts
@@ -1,21 +1,16 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 const { test } = Deno;
-import {
-  assertEquals,
-  assert,
-  assertThrows,
-  assertThrowsAsync
-} from "../../testing/asserts.ts";
+import { assertEquals, assertThrows, fail } from "../../testing/asserts.ts";
 import { appendFile, appendFileSync } from "./_fs_appendFile.ts";
 
 const decoder = new TextDecoder("utf-8");
 
 test({
   name: "No callback Fn results in Error",
-  async fn() {
-    await assertThrowsAsync(
-      async () => {
-        await appendFile("some/path", "some data", "utf8");
+  fn() {
+    assertThrows(
+      () => {
+        appendFile("some/path", "some data", "utf8");
       },
       Error,
       "No callback function supplied"
@@ -25,22 +20,17 @@ test({
 
 test({
   name: "Unsupported encoding results in error()",
-  async fn() {
-    await assertThrowsAsync(
-      async () => {
-        await appendFile(
-          "some/path",
-          "some data",
-          "made-up-encoding",
-          () => {}
-        );
+  fn() {
+    assertThrows(
+      () => {
+        appendFile("some/path", "some data", "made-up-encoding", () => {});
       },
       Error,
       "Only 'utf8' encoding is currently supported"
     );
-    await assertThrowsAsync(
-      async () => {
-        await appendFile(
+    assertThrows(
+      () => {
+        appendFile(
           "some/path",
           "some data",
           { encoding: "made-up-encoding" },
@@ -75,31 +65,47 @@ test({
       write: true,
       read: true
     });
-    let calledBack = false;
-    await appendFile(file.rid, "hello world", () => {
-      calledBack = true;
-    });
-    assert(calledBack);
-    Deno.close(file.rid);
-    const data = await Deno.readFile(tempFile);
-    assertEquals(decoder.decode(data), "hello world");
-    await Deno.remove(tempFile);
+    await new Promise((resolve, reject) => {
+      appendFile(file.rid, "hello world", err => {
+        if (err) reject();
+        else resolve();
+      });
+    })
+      .then(async () => {
+        const data = await Deno.readFile(tempFile);
+        assertEquals(decoder.decode(data), "hello world");
+      })
+      .catch(() => {
+        fail("No error expected");
+      })
+      .finally(async () => {
+        Deno.close(file.rid);
+        await Deno.remove(tempFile);
+      });
   }
 });
 
 test({
   name: "Async: Data is written to passed in file path",
   async fn() {
-    let calledBack = false;
     const openResourcesBeforeAppend: Deno.ResourceMap = Deno.resources();
-    await appendFile("_fs_appendFile_test_file.txt", "hello world", () => {
-      calledBack = true;
-    });
-    assert(calledBack);
-    assertEquals(Deno.resources(), openResourcesBeforeAppend);
-    const data = await Deno.readFile("_fs_appendFile_test_file.txt");
-    assertEquals(decoder.decode(data), "hello world");
-    await Deno.remove("_fs_appendFile_test_file.txt");
+    await new Promise((resolve, reject) => {
+      appendFile("_fs_appendFile_test_file.txt", "hello world", err => {
+        if (err) reject(err);
+        else resolve();
+      });
+    })
+      .then(async () => {
+        assertEquals(Deno.resources(), openResourcesBeforeAppend);
+        const data = await Deno.readFile("_fs_appendFile_test_file.txt");
+        assertEquals(decoder.decode(data), "hello world");
+      })
+      .catch(err => {
+        fail("No error was expected: " + err);
+      })
+      .finally(async () => {
+        await Deno.remove("_fs_appendFile_test_file.txt");
+      });
   }
 });
 
@@ -107,16 +113,23 @@ test({
   name:
     "Async: Callback is made with error if attempting to append data to an existing file with 'ax' flag",
   async fn() {
-    let calledBack = false;
     const openResourcesBeforeAppend: Deno.ResourceMap = Deno.resources();
     const tempFile: string = await Deno.makeTempFile();
-    await appendFile(tempFile, "hello world", { flag: "ax" }, (err: Error) => {
-      calledBack = true;
-      assert(err);
-    });
-    assert(calledBack);
-    assertEquals(Deno.resources(), openResourcesBeforeAppend);
-    await Deno.remove(tempFile);
+    await new Promise((resolve, reject) => {
+      appendFile(tempFile, "hello world", { flag: "ax" }, err => {
+        if (err) reject(err);
+        else resolve();
+      });
+    })
+      .then(() => {
+        fail("Expected error to be thrown");
+      })
+      .catch(() => {
+        assertEquals(Deno.resources(), openResourcesBeforeAppend);
+      })
+      .finally(async () => {
+        await Deno.remove(tempFile);
+      });
   }
 });