Add test for label generator

src/main/kotlin/com/dmdirc/ktirc/util/Labels.kt

 import com.dmdirc.ktirc.sasl.toBase64
 import java.time.ZoneOffset
 
-internal var generateLabel = { ircClient: IrcClient ->
+internal var generateLabel: (IrcClient) -> String = ::defaultGenerateLabel
+
+internal fun defaultGenerateLabel(ircClient: IrcClient): String {
     val time = currentTimeProvider().toEpochSecond(ZoneOffset.UTC)
     val counter = ircClient.serverState.labelCounter.incrementAndGet()
-    ByteArray(6) {
+    return ByteArray(6) {
         when {
             it < 3 -> (time shr it and 0xff).toByte()
             else -> (counter shr (it - 3) and 0xff).toByte()

src/test/kotlin/com/dmdirc/ktirc/IrcClientImplTest.kt

     }
 
     @Test
-    fun `sends text to socket without label if cap is missing`() = runBlocking {
+    fun `asynchronously sends text to socket without label if cap is missing`() = runBlocking {
         val client = IrcClientImpl(normalConfig)
         client.socketFactory = mockSocketFactory
         client.connect()
     }
 
     @Test
-    fun `sends text to socket with added tags and label`() = runBlocking {
+    fun `asynchronously sends text to socket with added tags and label`() = runBlocking {
         generateLabel = { "abc123" }
         val client = IrcClientImpl(normalConfig)
         client.socketFactory = mockSocketFactory
     }
 
     @Test
-    fun `sends tagged text to socket with label`() = runBlocking {
+    fun `asynchronously sends tagged text to socket with label`() = runBlocking {
         generateLabel = { "abc123" }
         val client = IrcClientImpl(normalConfig)
         client.socketFactory = mockSocketFactory

src/test/kotlin/com/dmdirc/ktirc/util/LabelsTest.kt

+package com.dmdirc.ktirc.util
+
+import com.dmdirc.ktirc.IrcClient
+import com.dmdirc.ktirc.TestConstants
+import com.dmdirc.ktirc.model.ServerState
+import io.mockk.every
+import io.mockk.mockk
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertNotEquals
+import org.junit.jupiter.api.Test
+
+internal class LabelsTest {
+
+    private val fakeServerState = ServerState("", "")
+    private val ircClient = mockk<IrcClient> {
+        every { serverState } returns fakeServerState
+    }
+
+    @Test
+    fun `increments the label id when generating labels`() {
+        assertEquals(0L, fakeServerState.labelCounter.get())
+        defaultGenerateLabel(ircClient)
+        assertEquals(1L, fakeServerState.labelCounter.get())
+        defaultGenerateLabel(ircClient)
+        assertEquals(2L, fakeServerState.labelCounter.get())
+    }
+
+    @Test
+    fun `generates unique labels in same instant`() {
+        currentTimeProvider = { TestConstants.time }
+        assertNotEquals(defaultGenerateLabel(ircClient), defaultGenerateLabel(ircClient))
+        assertNotEquals(defaultGenerateLabel(ircClient), defaultGenerateLabel(ircClient))
+    }
+
+    @Test
+    fun `generates unique labels at different times with the same counter value`() {
+        currentTimeProvider = { TestConstants.time }
+        val label1 = defaultGenerateLabel(ircClient)
+        fakeServerState.labelCounter.set(0L)
+        currentTimeProvider = { TestConstants.otherTime }
+        val label2 = defaultGenerateLabel(ircClient)
+        assertNotEquals(label1, label2)
+    }
+
+}