Move StringUtils to the main source set

Author: rhaendel

…de/ronny_h/aoc/extensions/StringUtils.kt …de/ronny_h/aoc/extensions/StringUtils.ktsrc/test/kotlin/de/ronny_h/aoc/extensions/StringUtils.kt renamed to src/main/kotlin/de/ronny_h/aoc/extensions/StringUtils.kt src/test/kotlin/de/ronny_h/aoc/extensions/StringUtils.kt renamed to src/main/kotlin/de/ronny_h/aoc/extensions/StringUtils.kt

@@ -0,0 +1,41 @@
+package de.ronny_h.aoc.extensions
+
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.matchers.shouldBe
+
+class StringUtilsTest : StringSpec({
+
+    "asList with a one-line String returns that String" {
+        "line one".asList() shouldBe listOf("line one")
+    }
+
+    "asList with an empty String returns a list containing an empty String" {
+        "".asList() shouldBe listOf("")
+    }
+
+    "asList converts a multiline String to a list of Strings with trimmed margin" {
+        """
+            line one
+            line two
+            line three
+        """.asList() shouldBe listOf("line one", "line two", "line three")
+    }
+
+    "asList preserves empty lines" {
+        """
+            line one
+
+            line two
+            line three
+
+        """.asList() shouldBe listOf("line one", "", "line two", "line three", "")
+    }
+
+    "asList does not trim single lines" {
+        """
+            line one
+            line two   
+            line three
+        """.asList() shouldBe listOf("line one", "line two   ", "line three")
+    }
+})