Fix tests to not log authentication data

We don't want to expose SMTP authentication details in tests, therefore the tests have been adjusted a bit

client.go

@@ -410,8 +410,11 @@ func (c *Client) SetSSL(s bool) {
 }
 
 // SetDebugLog tells the Client whether debug logging is enabled or not
-func (c *Client) SetDebugLog(s bool) {
+func (c *Client) SetDebugLog(v bool) {
-	c.dl = s
+	c.dl = v
+	if c.sc != nil {
+		c.sc.SetDebugLog(v)
+	}
 }
 
 // SetTLSConfig overrides the current *tls.Config with the given *tls.Config value
@@ -479,7 +482,7 @@ func (c *Client) DialWithContext(pc context.Context) error {
 		return err
 	}
 	if c.dl {
-		c.sc.SetDebugLog()
+		c.sc.SetDebugLog(true)
 	}
 	if err := c.sc.Hello(c.helo); err != nil {
 		return err

client_test.go

@@ -546,11 +546,10 @@ func TestClient_DialWithContext(t *testing.T) {
 // TestClient_DialWithContext_Debug tests the DialWithContext method for the Client object with debug
 // logging enabled on the SMTP client
 func TestClient_DialWithContext_Debug(t *testing.T) {
-	c, err := getTestConnection(true)
+	c, err := getTestClient(true)
 	if err != nil {
 		t.Skipf("failed to create test client: %s. Skipping tests", err)
 	}
-	c.SetDebugLog(true)
 	ctx := context.Background()
 	if err := c.DialWithContext(ctx); err != nil {
 		t.Errorf("failed to dial with context: %s", err)
@@ -562,6 +561,7 @@ func TestClient_DialWithContext_Debug(t *testing.T) {
 	if c.sc == nil {
 		t.Errorf("DialWithContext didn't fail but no SMTP client found.")
 	}
+	c.SetDebugLog(true)
 	if err := c.Close(); err != nil {
 		t.Errorf("failed to close connection: %s", err)
 	}
@@ -1141,6 +1141,8 @@ func getTestConnection(auth bool) (*Client, error) {
 		if p != "" {
 			c.SetPassword(p)
 		}
+		// We don't want to log authentication data in tests
+		c.SetDebugLog(false)
 	}
 	if err := c.DialWithContext(context.Background()); err != nil {
 		return c, fmt.Errorf("connection to test server failed: %w", err)
@@ -1151,6 +1153,51 @@ func getTestConnection(auth bool) (*Client, error) {
 	return c, nil
 }
 
+// getTestClient takes environment variables to establish a client without connecting
+// to the SMTP server
+func getTestClient(auth bool) (*Client, error) {
+	if os.Getenv("TEST_SKIP_ONLINE") != "" {
+		return nil, fmt.Errorf("env variable TEST_SKIP_ONLINE is set. Skipping online tests")
+	}
+	th := os.Getenv("TEST_HOST")
+	if th == "" {
+		return nil, fmt.Errorf("no TEST_HOST set")
+	}
+	tp := 25
+	if tps := os.Getenv("TEST_PORT"); tps != "" {
+		tpi, err := strconv.Atoi(tps)
+		if err == nil {
+			tp = tpi
+		}
+	}
+	sv := false
+	if sve := os.Getenv("TEST_TLS_SKIP_VERIFY"); sve != "" {
+		sv = true
+	}
+	c, err := NewClient(th, WithPort(tp))
+	if err != nil {
+		return c, err
+	}
+	c.tlsconfig.InsecureSkipVerify = sv
+	if auth {
+		st := os.Getenv("TEST_SMTPAUTH_TYPE")
+		if st != "" {
+			c.SetSMTPAuth(SMTPAuthType(st))
+		}
+		u := os.Getenv("TEST_SMTPAUTH_USER")
+		if u != "" {
+			c.SetUsername(u)
+		}
+		p := os.Getenv("TEST_SMTPAUTH_PASS")
+		if p != "" {
+			c.SetPassword(p)
+		}
+		// We don't want to log authentication data in tests
+		c.SetDebugLog(false)
+	}
+	return c, nil
+}
+
 // getTestConnectionWithDSN takes environment variables to establish a connection to a real
 // SMTP server to test all functionality that requires a connection. It also enables DSN
 func getTestConnectionWithDSN(auth bool) (*Client, error) {

smtp/smtp.go

@@ -432,9 +432,13 @@ func (c *Client) Quit() error {
 }
 
 // SetDebugLog enables the debug logging for incoming and outgoing SMTP messages
-func (c *Client) SetDebugLog() {
+func (c *Client) SetDebugLog(v bool) {
-	c.debug = true
+	c.debug = v
+	if v {
 		c.logger = log.New(os.Stderr, "[DEBUG] ", log.LstdFlags|log.Lmsgprefix)
+		return
+	}
+	c.logger = nil
 }
 
 // debugLog checks if the debug flag is set and if so logs the provided message to StdErr

smtp/smtp_test.go

@@ -655,7 +655,7 @@ func TestClient_SetDebugLog(t *testing.T) {
 	defer func() {
 		_ = c.Close()
 	}()
-	c.SetDebugLog()
+	c.SetDebugLog(true)
 	if !c.debug {
 		t.Errorf("Expected DebugLog flag to be true but received false")
 	}