fs: make callback mandatory to all async functions

The "fs" module has two functions called `maybeCallback` and
`makeCallback`, as of now.

The `maybeCallback` creates a default function to report errors, if the
parameter passed is not a function object. Basically, if the callback
is omitted in some cases, this function is used to create a default
callback function.

The `makeCallback`, OTOH, creates a default function only if the
parameter passed is `undefined`, and if it is not a function object it
will throw an `Error`.

This patch removes the `maybeCallback` function and makes the callback
function argument mandatory for all the async functions.

PR-URL: nodejs#7168
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

test/parallel/test-fs-chmod.js

@@ -101,7 +101,7 @@ fs.open(file2, 'a', function(err, fd) {
         assert.equal(mode_sync, fs.fstatSync(fd).mode & 0o777);
       }
       success_count++;
-      fs.close(fd);
+      fs.closeSync(fd);
     }
   });
 });

test/parallel/test-fs-link.js

@@ -23,14 +23,14 @@ fs.link(srcPath, dstPath, common.mustCall(callback));
 
 assert.throws(
   function() {
-    fs.link();
+    fs.link(undefined, undefined, () => {});
   },
   /src must be a string or Buffer/
 );
 
 assert.throws(
   function() {
-    fs.link('abc');
+    fs.link('abc', undefined, () => {});
   },
   /dest must be a string or Buffer/
 );

test/parallel/test-fs-make-callback.js

@@ -13,9 +13,6 @@ function test(cb) {
 // Verify the case where a callback function is provided
 assert.doesNotThrow(test(function() {}));
 
-// Passing undefined calls rethrow() internally, which is fine
-assert.doesNotThrow(test(undefined));
-
 // Anything else should throw
 assert.throws(test(null));
 assert.throws(test(true));

test/parallel/test-fs-mkdtemp.js

@@ -29,8 +29,3 @@ fs.mkdtemp(path.join(common.tmpDir, 'bar.'), common.mustCall(handler));
 // Same test as above, but making sure that passing an options object doesn't
 // affect the way the callback function is handled.
 fs.mkdtemp(path.join(common.tmpDir, 'bar.'), {}, common.mustCall(handler));
-
-// Making sure that not passing a callback doesn't crash, as a default function
-// is passed internally.
-assert.doesNotThrow(() => fs.mkdtemp(path.join(common.tmpDir, 'bar-')));
-assert.doesNotThrow(() => fs.mkdtemp(path.join(common.tmpDir, 'bar-'), {}));

test/parallel/test-fs-no-callback-errors.js

@@ -0,0 +1,17 @@
+'use strict';
+
+require('../common');
+const fs = require('fs');
+const assert = require('assert');
+
+Object.getOwnPropertyNames(fs).filter(
+  (d) => !d.endsWith('Stream') &&       // ignore stream creation functions
+         !d.endsWith('Sync') &&         // ignore synchronous functions
+         typeof fs[d] === 'function' && // ignore anything other than functions
+         d.indexOf('_') === -1 &&       // ignore internal use functions
+         !/^[A-Z]/.test(d) &&           // ignore conventional constructors
+         d !== 'watch' &&               // watch's callback is optional
+         d !== 'unwatchFile'            // unwatchFile's callback is optional
+).forEach(
+  (d) => assert.throws(() => fs[d](), /"callback" argument must be a function/)
+);

test/parallel/test-fs-stat.js

@@ -28,7 +28,7 @@ fs.open('.', 'r', undefined, common.mustCall(function(err, fd) {
   fs.fstat(fd, common.mustCall(function(err, stats) {
     assert.ifError(err);
     assert.ok(stats.mtime instanceof Date);
-    fs.close(fd);
+    fs.closeSync(fd);
     assert(this === global);
   }));
 
@@ -47,7 +47,7 @@ fs.open('.', 'r', undefined, common.mustCall(function(err, fd) {
     console.dir(stats);
     assert.ok(stats.mtime instanceof Date);
   }
-  fs.close(fd);
+  fs.closeSync(fd);
 }));
 
 console.log(`stating:  ${__filename}`);

test/parallel/test-fs-watchfile.js

@@ -8,11 +8,11 @@ const assert = require('assert');
 // Basic usage tests.
 assert.throws(function() {
   fs.watchFile('./some-file');
-}, /"watchFile\(\)" requires a listener function/);
+}, /"callback" argument must be a function/);
 
 assert.throws(function() {
   fs.watchFile('./another-file', {}, 'bad listener');
-}, /"watchFile\(\)" requires a listener function/);
+}, /"callback" argument must be a function/);
 
 assert.throws(function() {
   fs.watchFile(new Object(), function() {});