[Daemon] Add unit tests for LastDaemonCliOutputsTest

compiler/daemon/daemon-client/src/test/kotlin/LastDaemonCliOutputsTest.kt

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.daemon.client
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+
+class LastDaemonCliOutputsTest {
+    @Test
+    @DisplayName("adding lines and getting output as a single string")
+    fun fewLines() {
+        val daemonOutputs = LastDaemonCliOutputs()
+        daemonOutputs.add("Line 1")
+        daemonOutputs.add("Line 2")
+        daemonOutputs.add("Line 3")
+
+        val output = daemonOutputs.getAsSingleString()
+
+        assertEquals(
+            """
+            The daemon process output:
+                1. Line 1
+                2. Line 2
+                3. Line 3
+            """.trimIndent(), output
+        )
+    }
+
+    @Test
+    @DisplayName("getting output when no lines are added")
+    fun noLines() {
+        val daemonOutputs = LastDaemonCliOutputs()
+
+        val output = daemonOutputs.getAsSingleString()
+
+        assertEquals("    The daemon process produced no output", output)
+    }
+
+    @Test
+    @DisplayName("getting output with ellipsis for more lines")
+    fun withEllipsis() {
+        val daemonOutputs = LastDaemonCliOutputs()
+        repeat(15) { daemonOutputs.add("Line $it") }
+
+        val output = daemonOutputs.getAsSingleString()
+
+        assertEquals(
+            """
+            The daemon process output:
+                ... (5 more lines)
+                6. Line 5
+                7. Line 6
+                8. Line 7
+                9. Line 8
+                10. Line 9
+                11. Line 10
+                12. Line 11
+                13. Line 12
+                14. Line 13
+                15. Line 14
+            """.trimIndent(), output
+        )
+    }
+}