Added unit tests

src/test/java/org/opensearch/security/ssl/SecureSSLSettingsTest.java

@@ -0,0 +1,48 @@
+package org.opensearch.security.ssl;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import org.opensearch.common.settings.MockSecureSettings;
+import org.opensearch.common.settings.Settings;
+
+import static org.opensearch.security.ssl.SecureSSLSettings.SSLSetting.SECURITY_SSL_HTTP_PEMKEY_PASSWORD;
+
+public class SecureSSLSettingsTest {
+    @Test
+    public void testGetSettings() {
+        final var settings = SecureSSLSettings.getSecureSettings();
+        Assert.assertNotNull(settings);
+        Assert.assertTrue(settings.size() > 0);
+    }
+
+    @Test
+    public void testGetSecureSetting() {
+        final var mockSecureSettings = new MockSecureSettings();
+        mockSecureSettings.setString(SECURITY_SSL_HTTP_PEMKEY_PASSWORD.propertyName, "test-password");
+        final var settings = Settings.builder().setSecureSettings(mockSecureSettings).build();
+        final var password = SECURITY_SSL_HTTP_PEMKEY_PASSWORD.getSetting(settings);
+        Assert.assertEquals("test-password", password);
+    }
+
+    @Test
+    public void testGetInsecureSetting() {
+        final var settings = Settings.builder()
+                .put(SECURITY_SSL_HTTP_PEMKEY_PASSWORD.insecurePropertyName, "test-password")
+                .build();
+        final var password = SECURITY_SSL_HTTP_PEMKEY_PASSWORD.getSetting(settings);
+        Assert.assertEquals("test-password", password);
+    }
+
+    @Test
+    public void testShouldFavorSecureOverInsecureSetting() {
+        final var mockSecureSettings = new MockSecureSettings();
+        mockSecureSettings.setString(SECURITY_SSL_HTTP_PEMKEY_PASSWORD.propertyName, "secure-password");
+        final var settings = Settings.builder()
+                .setSecureSettings(mockSecureSettings)
+                .put(SECURITY_SSL_HTTP_PEMKEY_PASSWORD.insecurePropertyName, "insecure-password")
+                .build();
+        final var password = SECURITY_SSL_HTTP_PEMKEY_PASSWORD.getSetting(settings);
+        Assert.assertEquals("secure-password", password);
+    }
+}