Add AddDisposableDomains method #30 (#31)

handler.go

@@ -60,5 +60,10 @@ func updateDisposableDomains(source string) error {
 	for _, d := range domains {
 		disposableSyncDomains.Store(d, struct{}{})
 	}
+
+	// add additionalDisposableDomains again
+	for d := range additionalDisposableDomains {
+		disposableSyncDomains.Store(d, struct{}{})
+	}
 	return nil
 }

verifier.go

@@ -28,6 +28,9 @@ type Result struct {
 	HasMxRecords bool      `json:"has_mx_records"` // whether or not MX-Records for the domain
 }
 
+// additional list of disposable domains set via users of this library
+var additionalDisposableDomains map[string]bool = map[string]bool{}
+
 // init loads disposable_domain meta data to disposableSyncDomains which are safe for concurrent use
 func init() {
 	for d := range disposableDomains {
@@ -41,7 +44,6 @@ func NewVerifier() *Verifier {
 		fromEmail: defaultFromEmail,
 		helloName: defaultHelloName,
 	}
-
 }
 
 // Verify performs address, misc, mx and smtp checks
@@ -95,6 +97,15 @@ func (v *Verifier) Verify(email string) (*Result, error) {
 	return &ret, nil
 }
 
+// AddDisposableDomains adds additional domains as disposable domains.
+func (v *Verifier) AddDisposableDomains(domains []string) *Verifier {
+	for _, d := range domains {
+		additionalDisposableDomains[d] = true
+		disposableSyncDomains.Store(d, struct{}{})
+	}
+	return v
+}
+
 // EnableGravatarCheck enables check gravatar,
 // we don't check gravatar by default
 func (v *Verifier) EnableGravatarCheck() *Verifier {

verifier_test.go

@@ -192,6 +192,36 @@ func TestCheckEmail_Disposable(t *testing.T) {
 	assert.Equal(t, &expected, ret)
 }
 
+
+func TestCheckEmail_Disposable_override(t *testing.T) {
+	var (
+		username = "exampleuser"
+		domain   = "iamdisposableemail.test"
+		address  = username + "@" + domain
+		email    = address
+	)
+
+	verifier := NewVerifier().EnableSMTPCheck().AddDisposableDomains([]string{"iamdisposableemail.test"})
+	ret, err := verifier.Verify(email)
+	expected := Result{
+		Email: email,
+		Syntax: Syntax{
+			Username: username,
+			Domain:   domain,
+			Valid:    true,
+		},
+		HasMxRecords: false,
+		Reachable:    reachableUnknown,
+		Disposable:   true,
+		RoleAccount:  false,
+		Free:         false,
+		SMTP:         nil,
+	}
+	assert.Nil(t, err)
+	assert.Equal(t, &expected, ret)
+}
+
+
 func TestCheckEmail_RoleAccount(t *testing.T) {
 	var (
 		// trueVal  = true