update username regex

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@zeit/schemas",
-  "version": "2.36.0",
+  "version": "2.37.0",
   "description": "All schemas used for validation that are shared between our projects",
   "scripts": {
     "test": "yarn run lint && best --verbose",

test/user.js

@@ -25,7 +25,7 @@ exports.test_username_invalid_pattern = () => {
 	assert.equal(ajv.errors[0].dataPath, '.username');
 	assert.equal(
 		ajv.errors[0].message,
-		'should match pattern "^[a-z0-9][a-z0-9-]*[a-z0-9]$"'
+		'should match pattern "^(?!-)(?:[a-z0-9-]{1,48})(?<!-)$"'
 	);
 };
 
@@ -43,28 +43,36 @@ exports.test_username_too_short = () => {
 	assert.equal(ajv.errors[1].dataPath, '.username');
 	assert.equal(
 		ajv.errors[1].message,
-		'should match pattern "^[a-z0-9][a-z0-9-]*[a-z0-9]$"'
+		'should match pattern "^(?!-)(?:[a-z0-9-]{1,48})(?<!-)$"'
 	);
 };
 
 exports.test_username_too_long = () => {
-	const isValid = ajv.validate(User, {
-		username: 'a'.repeat(50)
-	});
+	const username = 'a'.repeat(50);
+	const isValid = ajv.validate(User, { username });
 	assert.equal(isValid, false);
-	assert.equal(ajv.errors.length, 1);
+	assert.equal(ajv.errors.length, 2);
 	assert.equal(ajv.errors[0].dataPath, '.username');
 	assert.equal(
 		ajv.errors[0].message,
 		'should NOT be longer than 48 characters'
 	);
+	assert.equal(
+		ajv.errors[1].message,
+		'should match pattern "^(?!-)(?:[a-z0-9-]{1,48})(?<!-)$"'
+	);
 };
 
 exports.test_username_valid = () => {
 	assert(ajv.validate(User, { username: 'n8' }));
 	assert(ajv.validate(User, { username: 'rauchg' }));
 };
 
+exports.test_username_one_char = () => {
+	assert(ajv.validate(User, { username: 'a' }));
+	assert(ajv.validate(User, { username: '1' }));
+};
+
 // Name
 exports.test_name_too_short = () => {
 	const isValid = ajv.validate(User, {

user/index.js

@@ -2,7 +2,7 @@ const Username = {
 	type: 'string',
 	minLength: 1,
 	maxLength: 48,
-	pattern: '^[a-z0-9][a-z0-9-]*[a-z0-9]$'
+	pattern: '^(?!-)(?:[a-z0-9-]{1,48})(?<!-)$'
 };
 
 const Name = {