Add tests for CharSequence extension functions

pgpainless-core/src/test/kotlin/openpgp/CharSequenceExtensionsTest.kt

@@ -0,0 +1,53 @@
+// SPDX-FileCopyrightText: 2024 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package openpgp
+
+import org.junit.jupiter.api.Assertions.assertArrayEquals
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+import org.pgpainless.util.Passphrase
+
+class CharSequenceExtensionsTest {
+
+    @Test
+    fun `toArray returns empty array for null`() {
+        assertArrayEquals(emptyArray(), (null as CharSequence?).toArray())
+    }
+
+    @Test
+    fun `toArray returns singleton array for non-null`() {
+        assertArrayEquals(arrayOf("foo"), "foo".toArray())
+    }
+
+    @Test
+    fun `toPassphrase returns emptyPassphrase for null`() {
+        assertEquals(Passphrase.emptyPassphrase(), (null as CharSequence?).toPassphrase())
+    }
+
+    @Test
+    fun `toPassphrase returns emptyPassphrase for empty string`() {
+        assertEquals(Passphrase.emptyPassphrase(), "".toPassphrase())
+    }
+
+    @Test
+    fun `toPassphrase returns emptyPassphrase for blank strings`() {
+        listOf(" ", "  ", "\t", "\t ", " \t", "\n", " \n", "\n ", "\r\n").forEach {
+            val passphrase = it.toPassphrase()
+            assertTrue(it.isBlank())
+            assertEquals(Passphrase.emptyPassphrase(), passphrase)
+        }
+    }
+
+    @Test
+    fun `toPassphrase returns non-empty passphrase for non-blank string`() {
+        listOf("sw0rdf1sh", "1", "foo", "bar", "dragon", "123456").forEach {
+            val passphrase = it.toPassphrase()
+            assertEquals(Passphrase.fromPassword(it), passphrase)
+            assertFalse(it.isBlank())
+        }
+    }
+}