Support granular diagnosis exclusion

Fixes #180. See also #162.

lib/index.js

@@ -197,6 +197,33 @@ internals.checkIpV6 = function (items) {
 };
 
 
+internals.isIterable = function (value) {
+
+    /* $lab:coverage:off$ */
+    if (!value) {
+        return false;
+    }
+    /* $lab:coverage:on$ */
+
+    if (typeof value !== 'object') {
+        return false;
+    }
+
+    // Return early in case we're on a version that doesn't support iterators.
+    if (Array.isArray(value)) {
+        return true;
+    }
+
+    /* $lab:coverage:off$ */
+    if (typeof Symbol === 'undefined') {
+        return false;
+    }
+    /* $lab:coverage:on$ */
+
+    return typeof value[Symbol.iterator] === 'function';
+};
+
+
 // Node 10 introduced isSet and isMap, which are useful for cross-context type
 // checking.
 // $lab:coverage:off$
@@ -368,10 +395,23 @@ exports.validate = internals.validate = function (email, options, callback) {
         throw new TypeError('expected positive integer minDomainAtoms');
     }
 
+    // Normalize the set of excluded diagnoses.
+    if (options.excludeDiagnoses) {
+        if (!internals.isIterable(options.excludeDiagnoses)) {
+            throw new TypeError('expected iterable excludeDiagnoses');
+        }
+
+        // This won't catch cross-realm Sets pre-Node 10, but it will cast the
+        // value to an in-realm Set representation.
+        if (!internals.isSet(options.excludeDiagnoses)) {
+            options.excludeDiagnoses = new Set(options.excludeDiagnoses);
+        }
+    }
+
     let maxResult = internals.diagnoses.valid;
     const updateResult = (value) => {
 
-        if (value > maxResult) {
+        if (value > maxResult && (!options.excludeDiagnoses || !options.excludeDiagnoses.has(value))) {
             maxResult = value;
         }
     };

test/index.js

@@ -184,6 +184,43 @@ describe('validate()', () => {
         })).to.equal(diag.rfc5321TLDNumeric);
     });
 
+    it('should ignore diagnoses in excludeDiagnoses', () => {
+
+        expect(() => {
+
+            Isemail.validate('person@123', { excludeDiagnoses: true });
+        }).to.throw(TypeError, /excludeDiagnoses/);
+
+        expect(() => {
+
+            Isemail.validate('person@123', {
+                excludeDiagnoses: {
+                    [diag.rfc5321TLDNumeric]: true
+                }
+            });
+        }).to.throw(TypeError, /excludeDiagnoses/);
+
+        expect(Isemail.validate('[email protected]', {
+            excludeDiagnoses: [diag.rfc5321AddressLiteral],
+            errorLevel: diag.rfc5321TLDNumeric
+        })).to.equal(diag.rfc5321TLDNumeric);
+
+        expect(Isemail.validate('person@[127.0.0.1]', {
+            excludeDiagnoses: [diag.rfc5321AddressLiteral],
+            errorLevel: diag.rfc5321TLDNumeric
+        })).to.equal(diag.valid);
+
+        expect(Isemail.validate('person@[127.0.0.1]', {
+            excludeDiagnoses: new Set([diag.rfc5321AddressLiteral]),
+            errorLevel: diag.rfc5321TLDNumeric
+        })).to.equal(diag.valid);
+
+        expect(Isemail.validate('person@[127.0.0.1]', {
+            excludeDiagnoses: [],
+            errorLevel: diag.rfc5321TLDNumeric
+        })).to.equal(diag.rfc5321AddressLiteral);
+    });
+
     it('should handle omitted options', () => {
 
         expect(Isemail.validate(expectations[0][0])).to.equal(expectations[0][1] < internals.defaultThreshold);