diff --git a/control_test.go b/control_test.go
new file mode 100644
index 00000000..725457b9
--- /dev/null
+++ b/control_test.go
@@ -0,0 +1,81 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+/* Tests performed:
+. Bad certificate
+. Bad private key
+. Valid certificate & private key */
+func TestValidateCertificates(t *testing.T) {
+	var data tlsConfig
+
+	// bad cert
+	data.CertificateChain = "bad cert"
+	data.PrivateKey = ""
+	data = validateCertificates(data)
+	if !(data.WarningValidation != "" &&
+		!data.ValidCert &&
+		!data.ValidChain) {
+		t.Fatalf("bad cert: validateCertificates(): %v", data)
+	}
+
+	// bad priv key
+	data.CertificateChain = ""
+	data.PrivateKey = "bad priv key"
+	data = validateCertificates(data)
+	if !(data.WarningValidation != "" &&
+		!data.ValidKey) {
+		t.Fatalf("bad priv key: validateCertificates(): %v", data)
+	}
+
+	// valid cert & priv key
+	data.CertificateChain = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`
+	data.PrivateKey = `-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----`
+	data = validateCertificates(data)
+	notBefore, _ := time.Parse(time.RFC3339, "2019-02-27T09:24:23Z")
+	notAfter, _ := time.Parse(time.RFC3339, "2046-07-14T09:24:23Z")
+	if !(data.WarningValidation != "" /* self signed */ &&
+		data.ValidCert &&
+		!data.ValidChain &&
+		data.ValidKey &&
+		data.KeyType == "RSA" &&
+		data.Subject == "CN=AdGuard Home,O=AdGuard Ltd" &&
+		data.Issuer == "CN=AdGuard Home,O=AdGuard Ltd" &&
+		data.NotBefore == notBefore &&
+		data.NotAfter == notAfter &&
+		// data.DNSNames[0] ==  &&
+		data.usable) {
+		t.Fatalf("valid cert & priv key: validateCertificates(): %v", data)
+	}
+}