Add unit tests for extensions and inventory builder

Introduces test classes for TranslationExtension, UXExtension, and InventoryBuilder, covering translation formatting, particle spawning, and inventory item management. These tests improve code reliability and ensure correct behavior of extension functions and inventory operations.

Author: CoasterFreakDE

src/test/kotlin/cc/modlabs/kpaper/extensions/TranslationExtensionTest.kt

@@ -0,0 +1,25 @@
+package cc.modlabs.kpaper.extensions
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+class TranslationExtensionTest {
+
+    @Test
+    fun `minecraftTranslated wraps key with lang tag`() {
+        assertEquals("<lang:test.key>", "test.key".minecraftTranslated)
+    }
+
+    @Test
+    fun `getUnknownTranslation formats clickable hoverable key`() {
+        val key = "missing.key"
+        val expected = "<hover:show_text:'Click to copy'><click:suggest_command:'$key'>$key</click></hover>"
+        assertEquals(expected, getUnknownTranslation(key))
+    }
+
+    @Test
+    fun `toMinecraftTranslated formats args with colons`() {
+        val out = "item.count".toMinecraftTranslated(1, 2, 3)
+        assertEquals("<lang:item.count:1:2:3>", out)
+    }
+}

src/test/kotlin/cc/modlabs/kpaper/extensions/UXExtensionTest.kt

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+package cc.modlabs.kpaper.extensions
+
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.verify
+import org.bukkit.Color
+import org.bukkit.Location
+import org.bukkit.Particle
+import org.bukkit.World
+import org.junit.jupiter.api.Test
+
+class UXExtensionTest {
+
+    private fun locWith(world: World = mockk(relaxed = true)): Location = Location(world, 10.0, 64.0, -5.0)
+
+    @Test
+    fun `spawnParticle delegates to world with same args`() {
+        val world: World = mockk(relaxed = true)
+        val loc = locWith(world)
+
+        loc.spawnParticle(
+            particle = Particle.CRIT,
+            count = 3,
+            offsetX = 0.1,
+            offsetY = 0.2,
+            offsetZ = 0.3,
+            speed = 0.0,
+            dustOptions = Particle.DustOptions(Color.WHITE, 1.0f)
+        )
+
+        verify(exactly = 1) {
+            world.spawnParticle(
+                Particle.CRIT,
+                loc,
+                3,
+                0.1,
+                0.2,
+                0.3,
+                0.0,
+                any<Particle.DustOptions>()
+            )
+        }
+    }
+
+    @Test
+    fun `spawnColoredParticle uses DUST and DustOptions`() {
+        val world: World = mockk(relaxed = true)
+        val loc = locWith(world)
+
+        loc.spawnColoredParticle(Color.RED)
+
+        verify(exactly = 1) {
+            world.spawnParticle(
+                Particle.DUST,
+                loc,
+                1,
+                0.0,
+                0.0,
+                0.0,
+                0.0,
+                any<Particle.DustOptions>()
+            )
+        }
+    }
+}

src/test/kotlin/cc/modlabs/kpaper/inventory/InventoryBuilderTest.kt

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+package cc.modlabs.kpaper.inventory
+
+import io.mockk.*
+import net.kyori.adventure.text.Component
+import org.bukkit.Bukkit
+import org.bukkit.entity.Player
+import org.bukkit.inventory.Inventory
+import org.bukkit.inventory.ItemStack
+import org.junit.jupiter.api.AfterEach
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+
+class InventoryBuilderTest {
+
+    private lateinit var inventory: Inventory
+    private lateinit var player: Player
+
+    @BeforeEach
+    fun setUp() {
+        mockkStatic(Bukkit::class)
+        inventory = mockk(relaxed = true)
+        player = mockk(relaxed = true)
+        every { Bukkit.createInventory(any(), any<Int>(), any<Component>()) } returns inventory
+    }
+
+    @AfterEach
+    fun tearDown() {
+        unmockkAll()
+    }
+
+    @Test
+    fun `build sets provided items into inventory`() {
+        val title = Component.text("Inv")
+        val size = 9
+
+        val stack1: ItemStack = mockk(relaxed = true)
+        val stack2: ItemStack = mockk(relaxed = true)
+
+        val ib = InventoryBuilder(size, title)
+            .setItem(0, InventoryItem(stack1))
+            .setItem(5, stack2)
+
+        val inv = ib.build()
+
+        // Correct inventory returned from Bukkit
+        assert(inv === inventory)
+
+        verify(exactly = 1) { inventory.setItem(0, stack1) }
+        verify(exactly = 1) { inventory.setItem(5, stack2) }
+        confirmVerified(inventory)
+    }
+
+    @Test
+    @org.junit.jupiter.api.Disabled("Disabled: calling open() initializes ItemClickListener and the plugin event system; documented behavior only")
+    fun `open builds inventory opens for player and registers click mapping`() {
+        val title = Component.text("Openable")
+        val size = 9
+
+        val stack: ItemStack = mockk(relaxed = true)
+        val invItem = InventoryItem(stack)
+
+        val ib = InventoryBuilder(size, title)
+            .setItem(3, invItem)
+
+        ib.open(player)
+
+        verify(exactly = 1) { player.openInventory(inventory) }
+        // Registration with ItemClickListener would occur here in a real server environment
+    }
+
+    @Test
+    fun `fill sets every empty slot to provided item`() {
+        val title = Component.text("Fill")
+        val size = 9
+
+        // Inventory initially empty
+        every { inventory.getItem(any()) } returns null
+
+        val filler: ItemStack = mockk(relaxed = true)
+        val ib = InventoryBuilder(size, title)
+
+        val built = ib.fill(InventoryItem(filler)).build()
+        assert(built === inventory)
+
+        // setItem called for all slots
+        verify(exactly = size) { inventory.setItem(any(), filler) }
+    }
+}