Add comprehensive tests for Pair class

Add 15 unit tests covering getKey(), getValue(), equals(), hashCode(), and
toString() methods. Tests include edge cases with null values and different
generic types.

https://claude.ai/code/session_01T7864vnS6vc9W1PbHRzCK4

Author: claude

src/test/java/de/kherud/llama/PairTest.java

@@ -0,0 +1,138 @@
+package de.kherud.llama;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class PairTest {
+
+	@Test
+	public void testGetKey() {
+		Pair<String, Integer> pair = new Pair<>("key1", 42);
+		assertEquals("key1", pair.getKey());
+	}
+
+	@Test
+	public void testGetValue() {
+		Pair<String, Integer> pair = new Pair<>("key1", 42);
+		assertEquals(Integer.valueOf(42), pair.getValue());
+	}
+
+	@Test
+	public void testGetKeyWithNullValue() {
+		Pair<String, Integer> pair = new Pair<>("key1", null);
+		assertEquals("key1", pair.getKey());
+		assertNull(pair.getValue());
+	}
+
+	@Test
+	public void testGetKeyWithNullKey() {
+		Pair<String, Integer> pair = new Pair<>(null, 42);
+		assertNull(pair.getKey());
+		assertEquals(Integer.valueOf(42), pair.getValue());
+	}
+
+	@Test
+	public void testEqualsWithSamePair() {
+		Pair<String, Integer> pair1 = new Pair<>("key", 123);
+		Pair<String, Integer> pair2 = new Pair<>("key", 123);
+		assertEquals(pair1, pair2);
+	}
+
+	@Test
+	public void testEqualsWithDifferentKey() {
+		Pair<String, Integer> pair1 = new Pair<>("key1", 123);
+		Pair<String, Integer> pair2 = new Pair<>("key2", 123);
+		assertNotEquals(pair1, pair2);
+	}
+
+	@Test
+	public void testEqualsWithDifferentValue() {
+		Pair<String, Integer> pair1 = new Pair<>("key", 123);
+		Pair<String, Integer> pair2 = new Pair<>("key", 456);
+		assertNotEquals(pair1, pair2);
+	}
+
+	@Test
+	public void testEqualsWithNull() {
+		Pair<String, Integer> pair = new Pair<>("key", 123);
+		assertNotEquals(pair, null);
+	}
+
+	@Test
+	public void testEqualsWithDifferentClass() {
+		Pair<String, Integer> pair = new Pair<>("key", 123);
+		assertNotEquals(pair, "not a pair");
+	}
+
+	@Test
+	public void testEqualsSameInstance() {
+		Pair<String, Integer> pair = new Pair<>("key", 123);
+		assertEquals(pair, pair);
+	}
+
+	@Test
+	public void testEqualsWithBothNullKeyAndValue() {
+		Pair<String, Integer> pair1 = new Pair<>(null, null);
+		Pair<String, Integer> pair2 = new Pair<>(null, null);
+		assertEquals(pair1, pair2);
+	}
+
+	@Test
+	public void testHashCodeSamePair() {
+		Pair<String, Integer> pair1 = new Pair<>("key", 123);
+		Pair<String, Integer> pair2 = new Pair<>("key", 123);
+		assertEquals(pair1.hashCode(), pair2.hashCode());
+	}
+
+	@Test
+	public void testHashCodeDifferentPairs() {
+		Pair<String, Integer> pair1 = new Pair<>("key1", 123);
+		Pair<String, Integer> pair2 = new Pair<>("key2", 456);
+		// Different pairs may have different hash codes (not guaranteed, but likely)
+		// We mostly check that hashCode() doesn't throw
+		assertNotNull(pair1.hashCode());
+		assertNotNull(pair2.hashCode());
+	}
+
+	@Test
+	public void testHashCodeWithNull() {
+		Pair<String, Integer> pair = new Pair<>(null, null);
+		// Should not throw when hashing null values
+		assertNotNull(pair.hashCode());
+	}
+
+	@Test
+	public void testToString() {
+		Pair<String, Integer> pair = new Pair<>("testKey", 42);
+		String result = pair.toString();
+		assertTrue(result.contains("Pair"));
+		assertTrue(result.contains("testKey"));
+		assertTrue(result.contains("42"));
+	}
+
+	@Test
+	public void testToStringWithNull() {
+		Pair<String, Integer> pair = new Pair<>(null, 42);
+		String result = pair.toString();
+		assertTrue(result.contains("Pair"));
+		assertTrue(result.contains("null"));
+	}
+
+	@Test
+	public void testPairWithDifferentTypes() {
+		Pair<Integer, Double> pair = new Pair<>(10, 3.14);
+		assertEquals(Integer.valueOf(10), pair.getKey());
+		assertEquals(Double.valueOf(3.14), pair.getValue());
+	}
+
+	@Test
+	public void testPairWithComplexTypes() {
+		Pair<String[], Integer[]> pair = new Pair<>(
+			new String[]{"a", "b"},
+			new Integer[]{1, 2}
+		);
+		assertArrayEquals(new String[]{"a", "b"}, pair.getKey());
+		assertArrayEquals(new Integer[]{1, 2}, pair.getValue());
+	}
+}