Simplify format checks

src/format.spec.ts

@@ -5,10 +5,7 @@ describe('format(credentials)', function () {
   describe('arguments', function () {
     describe('credentials', function () {
       it('should be required', function () {
-        assert.throws(
-          () => (format as any)(),
-          /argument credentials is required/,
-        );
+        assert.throws(() => (format as any)(), /credentials is required/);
       });
 
       it('should accept credentials', function () {
@@ -19,63 +16,57 @@ describe('format(credentials)', function () {
       it('should reject null', function () {
         assert.throws(
           format.bind(null, null as any),
-          /argument credentials is required/,
+          /credentials is required/,
         );
       });
 
       it('should reject a number', function () {
-        assert.throws(
-          format.bind(null, 42 as any),
-          /argument credentials is required/,
-        );
+        assert.throws(format.bind(null, 42 as any), /credentials is required/);
       });
 
       it('should reject a string', function () {
-        assert.throws(
-          format.bind(null, '' as any),
-          /argument credentials is required/,
-        );
+        assert.throws(format.bind(null, '' as any), /credentials is required/);
       });
 
       it('should reject an object without name', function () {
         assert.throws(
           format.bind(null, { pass: 'bar' } as any),
-          /argument credentials is required to have name and pass properties/,
+          /credentials is required to have name and pass properties/,
         );
       });
 
       it('should reject an object without pass', function () {
         assert.throws(
           format.bind(null, { name: 'foo' } as any),
-          /argument credentials is required to have name and pass properties/,
+          /credentials is required to have name and pass properties/,
         );
       });
 
       it('should reject an object with non-string name', function () {
         assert.throws(
           format.bind(null, { name: 42, pass: 'bar' } as any),
-          /argument credentials is required to have name and pass properties/,
+          /credentials is required to have name and pass properties/,
         );
       });
 
       it('should reject an object with non-string pass', function () {
         assert.throws(
           format.bind(null, { name: 'foo', pass: 42 } as any),
-          /argument credentials is required to have name and pass properties/,
+          /credentials is required to have name and pass properties/,
         );
       });
 
       it('should reject userid containing colon', function () {
         assert.throws(
           format.bind(null, { name: 'foo:bar', pass: 'baz' }),
-          /must not contain a colon or control characters/,
+          /must not contain a colon/,
         );
       });
 
       it('should reject control chars in userid', function () {
         assert.throws(
           format.bind(null, { name: 'foo\u0000bar', pass: 'baz' }),
-          /must not contain a colon or control characters/,
+          /must not contain control characters/,
         );
       });
 

src/index.ts

@@ -52,39 +52,33 @@ export function parse(string: string): Credentials | undefined {
  * @public
  */
 export function format(credentials: Credentials): string {
-  if (!credentials) {
-    throw new TypeError('argument credentials is required');
-  }
-
-  if (typeof credentials !== 'object') {
-    throw new TypeError('argument credentials is required to be an object');
+  if (typeof credentials !== 'object' || credentials === null) {
+    throw new TypeError('credentials is required to be an object');
   }
 
   if (
     typeof credentials.name !== 'string' ||
     typeof credentials.pass !== 'string'
   ) {
     throw new TypeError(
-      'argument credentials is required to have name and pass properties',
+      'credentials is required to have name and pass properties',
     );
   }
 
-  if (
-    credentials.name.includes(':') || // RFC 7617 disallows colon in username
-    CONTROL_CHARS_REGEXP.test(credentials.name)
-  ) {
-    throw new TypeError(
-      'argument credentials.name must not contain a colon or control characters',
-    );
+  // RFC 7617 disallows colon in username
+  if (credentials.name.includes(':')) {
+    throw new TypeError('name must not contain a colon');
   }
 
-  if (CONTROL_CHARS_REGEXP.test(credentials.pass)) {
+  const str = credentials.name + ':' + credentials.pass;
+
+  if (CONTROL_CHARS_REGEXP.test(str)) {
     throw new TypeError(
-      'argument credentials.pass must not contain control characters',
+      'argument credentials must not contain control characters',
     );
   }
 
-  return 'Basic ' + base64.encode(credentials.name + ':' + credentials.pass);
+  return 'Basic ' + base64.encode(str);
 }
 
 /**