test: Add several test cases

- Added a test to check whether the `options` argument of APIs allows explicit `null` value
- Added a test to check whether the `ls` function accepts a string value of `lsTypes` property names as value of `type` argument
- Added a test to check the `ls` function correctly throws a `TypeError` if the given `type` argument is an unexpected value

test/lsfnd.spec.cjs

@@ -27,6 +27,12 @@ it('test `lsFiles` function by listing this file directory', async () => {
   deepEq(results, expected);
 }, false);
 
+it('test `lsDirs` function by listing this file directory', async () => {
+  const results = await lsDirs(__dirname);
+  const expected = [ 'lib' ].map((e) => path.join(__dirname, e));
+  deepEq(results, expected);
+}, false);
+
 it('list root directory using URL object', async () => {
   await doesNotReject(ls(pathToFileURL(rootDirPosix)), URIError);
 }, false);
@@ -35,17 +41,27 @@ it('list root directory using file URL path', async () => {
   await doesNotReject(ls('file:'.concat(rootDirPosix)), URIError);
 }, false);
 
-it('test `lsDirs` function by listing this file directory', async () => {
-  const results = await lsDirs(__dirname);
-  const expected = [ 'lib' ].map((e) => path.join(__dirname, e));
-  deepEq(results, expected);
+it('test if the options argument allows explicit null value', async () => {
+  await doesNotReject(lsFiles(__dirname, null), TypeError);
+}, false);
+
+it('test if the type argument accepts a string value', async () => {
+  await doesNotReject(ls(__dirname, {}, 'LS_D'), TypeError);
 }, false);
 
 it('throws an error if the given directory path not exist', async () => {
   await rejects(ls('./this/is/not/exist/directory/path'), Error);
 }, false);
 
-it('throws an URIError if the given file URL path using unsupported protocol',
+it('throws a `URIError` if the given file URL path using unsupported protocol',
   async () => await rejects(ls('http:'.concat(rootDirPosix)), URIError),
   false
 );
+
+it('throws a `TypeError` if the given type is an unexpected value',
+  async () => {
+    await rejects(ls(__dirname, {}, 'LS_FOO'), TypeError);  // Invalid string value test
+    await rejects(ls(__dirname, {}, []), TypeError);        // Array test
+  },
+  false
+);

test/lsfnd.spec.mjs

@@ -45,6 +45,14 @@ it('list root directory using file URL path', async () => {
   await doesNotReject(ls('file:'.concat(rootDirPosix)), URIError);
 }, false);
 
+it('test if the options argument allows explicit null value', async () => {
+  await doesNotReject(lsFiles(__dirname, null), TypeError);
+}, false);
+
+it('test if the type argument accepts a string value', async () => {
+  await doesNotReject(ls(__dirname, {}, 'LS_D'), TypeError);
+}, false);
+
 it('throws an error if the given directory path not exist', async () => {
   await rejects(ls('./this/is/not/exist/directory/path'), Error);
 }, false);
@@ -53,3 +61,11 @@ it('throws an URIError if the given file URL path using unsupported protocol',
   async () => await rejects(ls('http:'.concat(rootDirPosix)), URIError),
   false
 );
+
+it('throws a `TypeError` if the given type is an unexpected value',
+  async () => {
+    await rejects(ls(__dirname, {}, 'LS_FOO'), TypeError);  // Invalid string value test
+    await rejects(ls(__dirname, {}, []), TypeError);        // Array test
+  },
+  false
+);