diff --git a/src/functionalTest/java/codechicken/multipart/test/ControlKeyModiferFunctionalTest.java b/src/functionalTest/java/codechicken/multipart/test/ControlKeyModiferFunctionalTest.java
new file mode 100644
index 0000000..bd9d795
--- /dev/null
+++ b/src/functionalTest/java/codechicken/multipart/test/ControlKeyModiferFunctionalTest.java
@@ -0,0 +1,76 @@
+package codechicken.multipart.test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.world.WorldServer;
+import net.minecraftforge.common.util.FakePlayerFactory;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import codechicken.multipart.ControlKeyModifer;
+
+/**
+ * isControlDown needs a player with a world to pick its branch. On a dedicated server the world is never remote, so
+ * these cover the server half: the map the client keeps in sync through packet 1. The client half reads
+ * isClientPressing instead and no test harness has a client.
+ */
+class ControlKeyModiferFunctionalTest {
+
+    @BeforeEach
+    @AfterEach
+    void clearRecordedPlayers() {
+        clearAll();
+    }
+
+    @Test
+    void aPlayerTheServerHasNotHeardFromIsNotHoldingTheKey() {
+        assertFalse(ControlKeyModifer.isControlDown(player()));
+    }
+
+    @Test
+    void reflectsWhatTheServerLastRecordedForThePlayer() {
+        EntityPlayer player = player();
+
+        record(player, true);
+        assertTrue(ControlKeyModifer.isControlDown(player));
+
+        record(player, false);
+        assertFalse(ControlKeyModifer.isControlDown(player));
+    }
+
+    /** Server stop clears the map, so a player must not carry a held key into the next run. */
+    @Test
+    void clearingResetsThePlayerToNotHolding() {
+        EntityPlayer player = player();
+        record(player, true);
+
+        clearAll();
+
+        assertFalse(ControlKeyModifer.isControlDown(player));
+    }
+
+    // The two adapters below are the only places the map's collection type is named.
+
+    private static void record(EntityPlayer player, boolean pressed) {
+        ControlKeyModifer.map().put(player, pressed);
+    }
+
+    private static void clearAll() {
+        ControlKeyModifer.map().clear();
+    }
+
+    private static EntityPlayer player() {
+        WorldServer world = MinecraftServer.getServer().worldServers[0];
+        assertNotNull(world);
+        EntityPlayer player = FakePlayerFactory.getMinecraft(world);
+        assertNotNull(player);
+        assertFalse(player.worldObj.isRemote, "A dedicated server world is never remote");
+        return player;
+    }
+}
diff --git a/src/test/java/codechicken/multipart/ControlKeyModiferCharacterizationTest.java b/src/test/java/codechicken/multipart/ControlKeyModiferCharacterizationTest.java
new file mode 100644
index 0000000..4da0461
--- /dev/null
+++ b/src/test/java/codechicken/multipart/ControlKeyModiferCharacterizationTest.java
@@ -0,0 +1,35 @@
+package codechicken.multipart;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+
+import net.minecraft.entity.player.EntityPlayer;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Every branch of isControlDown needs a player with a world, so the behavior is covered by the Forge server suite
+ * against a FakePlayer. What is pinned here is the Java-facing entry point, which the reference scaladoc calls out as
+ * existing for Java callers rather than for the Scala implicit.
+ */
+class ControlKeyModiferCharacterizationTest {
+
+    /** The class name carries a typo in the reference. It is the published name, so the port keeps it. */
+    @Test
+    void theTypoInTheClassNameIsPreserved() {
+        assertEquals("codechicken.multipart.ControlKeyModifer", ControlKeyModifer.class.getName());
+    }
+
+    @Test
+    void theJavaFacingQueryIsAPublicStaticTakingAPlayer() throws Exception {
+        Method isControlDown = ControlKeyModifer.class.getDeclaredMethod("isControlDown", EntityPlayer.class);
+
+        assertSame(boolean.class, isControlDown.getReturnType());
+        assertTrue(Modifier.isPublic(isControlDown.getModifiers()));
+        assertTrue(Modifier.isStatic(isControlDown.getModifiers()));
+    }
+}