Implement E-mail Arbitrary

Fixes: #303

documentation/Arbitraries.md

@@ -76,6 +76,7 @@ More specific strings:
 - `fc.webQueryParameters()` Query parameters to build an URI. Fragment is the optional part right after the ? in an URI
 - `fc.webSegment()` Web URL path segment
 - `fc.webUrl()` Web URL following the specs specified by RFC 3986 and WHATWG URL Standard
+- `fc.emailAddress()` Email address following RFC 1123 and RFC 5322
 
 ## Combinors of arbitraries (:T)
 

src/check/arbitrary/EmailArbitrary.ts

@@ -0,0 +1,17 @@
+import { array } from './ArrayArbitrary';
+import { buildLowerAlphaNumericArb } from './helpers/SpecificCharacterRange';
+import { domain } from './HostArbitrary';
+import { stringOf } from './StringArbitrary';
+import { tuple } from './TupleArbitrary';
+
+/**
+ * For email address
+ *
+ * According to RFC 5322 - https://www.ietf.org/rfc/rfc5322.txt
+ */
+export function emailAddress() {
+  const others = ['!', '#', '$', '%', '&', "'", '*', '+', '-', '/', '=', '?', '^', '_', '`', '{', '|', '}', '~'];
+  const atextArb = buildLowerAlphaNumericArb(others);
+  const dotAtomArb = array(stringOf(atextArb, 1, 10), 1, 5).map(a => a.join('.'));
+  return tuple(dotAtomArb, domain()).map(([lp, d]) => `${lp}@${d}`);
+}

src/fast-check-default.ts

@@ -16,6 +16,7 @@ import { dedup } from './check/arbitrary/DedupArbitrary';
 import { Arbitrary } from './check/arbitrary/definition/Arbitrary';
 import { Shrinkable } from './check/arbitrary/definition/Shrinkable';
 import { dictionary } from './check/arbitrary/DictionaryArbitrary';
+import { emailAddress } from './check/arbitrary/EmailArbitrary';
 import { double, float } from './check/arbitrary/FloatingPointArbitrary';
 import { frequency } from './check/arbitrary/FrequencyArbitrary';
 import { compareBooleanFunc, compareFunc, func } from './check/arbitrary/FunctionArbitrary';
@@ -157,6 +158,7 @@ export {
   webFragments,
   webQueryParameters,
   webUrl,
+  emailAddress,
   // model-based
   AsyncCommand,
   Command,

test/unit/check/arbitrary/EmailArbitrary.spec.ts

@@ -0,0 +1,30 @@
+import { emailAddress } from '../../../../src/check/arbitrary/EmailArbitrary';
+
+import * as genericHelper from './generic/GenericArbitraryHelper';
+
+const isValidEmailRfc1123 = (t: string) => {
+  // Taken from https://www.w3.org/TR/html5/forms.html#valid-e-mail-address
+  const rfc1123 = /^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/;
+  return rfc1123.test(t);
+};
+
+const isValidEmailRfc5322 = (t: string) => {
+  // Taken from https://stackoverflow.com/questions/201323/how-to-validate-an-email-address-using-a-regular-expression
+  const rfc5322 = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
+  return rfc5322.test(t);
+};
+
+describe('EmailArbitrary', () => {
+  describe('emailAddress', () => {
+    describe('RFC 1123', () => {
+      genericHelper.isValidArbitrary(() => emailAddress(), {
+        isValidValue: (g: string) => isValidEmailRfc1123(g)
+      });
+    });
+    describe('RFC 5322', () => {
+      genericHelper.isValidArbitrary(() => emailAddress(), {
+        isValidValue: (g: string) => isValidEmailRfc5322(g)
+      });
+    });
+  });
+});