Add junit test of Passphrase

pgpainless-core/src/test/java/org/pgpainless/key/protection/PassphraseTest.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pgpainless.key.protection;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import org.junit.Test;
+import org.pgpainless.util.Passphrase;
+
+public class PassphraseTest {
+
+    @Test
+    public void testGetAndClear() {
+        Passphrase passphrase = new Passphrase("secret".toCharArray());
+
+        assertArrayEquals("secret".toCharArray(), passphrase.getChars());
+        assertTrue(passphrase.isValid());
+
+        passphrase.clear();
+
+        assertFalse(passphrase.isValid());
+        try {
+            passphrase.getChars();
+            fail();
+        } catch (IllegalStateException e) {
+            // expected
+        }
+    }
+}