Add test for CompressionAlgorithmNegotiator

pgpainless-core/src/main/kotlin/org/pgpainless/algorithm/negotiation/CompressionAlgorithmNegotiator.kt

@@ -8,13 +8,31 @@ import org.pgpainless.algorithm.CompressionAlgorithm
 import org.pgpainless.policy.Policy
 
 fun interface CompressionAlgorithmNegotiator {
+
+    /**
+     * Negotiate a suitable [CompressionAlgorithm] by taking into consideration the [Policy], a
+     * user-provided [compressionAlgorithmOverride] and the users set of [orderedPreferences].
+     *
+     * @param policy implementations [Policy]
+     * @param compressionAlgorithmOverride user-provided [CompressionAlgorithm] override.
+     * @param orderedPreferences preferred compression algorithms taken from the users certificate
+     * @return negotiated [CompressionAlgorithm]
+     */
     fun negotiate(
         policy: Policy,
-        override: CompressionAlgorithm?,
+        compressionAlgorithmOverride: CompressionAlgorithm?,
         orderedPreferences: Set<CompressionAlgorithm>?
     ): CompressionAlgorithm
 
     companion object {
+
+        /**
+         * Static negotiation of compression algorithms. This implementation discards compression
+         * algorithm preferences and instead either returns the non-null algorithm override,
+         * otherwise the policies default hash algorithm.
+         *
+         * @return delegate implementation
+         */
         @JvmStatic
         fun staticNegotiation(): CompressionAlgorithmNegotiator =
             CompressionAlgorithmNegotiator { policy, override, _ ->

pgpainless-core/src/test/java/org/pgpainless/algorithm/negotiation/CompressionAlgorithmNegotiatorTest.java

@@ -0,0 +1,52 @@
+// SPDX-FileCopyrightText: 2025 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.algorithm.negotiation;
+
+import org.junit.jupiter.api.Test;
+import org.pgpainless.PGPainless;
+import org.pgpainless.algorithm.CompressionAlgorithm;
+import org.pgpainless.policy.Policy;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class CompressionAlgorithmNegotiatorTest {
+
+    @Test
+    public void staticNegotiateWithoutOverride() {
+        Policy policy = PGPainless.getInstance().getAlgorithmPolicy()
+                .copy()
+                .withCompressionAlgorithmPolicy(new Policy.CompressionAlgorithmPolicy(
+                        CompressionAlgorithm.BZIP2,
+                        Arrays.asList(CompressionAlgorithm.BZIP2, CompressionAlgorithm.UNCOMPRESSED)
+                ))
+                .build();
+        CompressionAlgorithmNegotiator negotiator = CompressionAlgorithmNegotiator.staticNegotiation();
+
+        // If the user did not pass an override, return the policy default
+        assertEquals(
+                CompressionAlgorithm.BZIP2,
+                negotiator.negotiate(policy, null, Collections.emptySet()));
+    }
+
+    @Test
+    public void staticNegotiateWithOverride() {
+        Policy policy = PGPainless.getInstance().getAlgorithmPolicy()
+                .copy()
+                .withCompressionAlgorithmPolicy(new Policy.CompressionAlgorithmPolicy(
+                        CompressionAlgorithm.BZIP2,
+                        Arrays.asList(CompressionAlgorithm.BZIP2, CompressionAlgorithm.UNCOMPRESSED)
+                ))
+                .build();
+        CompressionAlgorithmNegotiator negotiator = CompressionAlgorithmNegotiator.staticNegotiation();
+
+        // If the user passed an override, return that
+        assertEquals(
+                CompressionAlgorithm.ZLIB,
+                negotiator.negotiate(policy, CompressionAlgorithm.ZLIB, Collections.emptySet()));
+    }
+}