Fixes some problems with TabCompletionHelper.getStringList

src/main/java/net/knarcraft/knarlib/util/TabCompletionHelper.java

@@ -38,7 +38,14 @@ public final class TabCompletionHelper {
         } else {
             // The argument base is everything the player has typed, until the last comma
             List<String> arguments = List.of(typedText.split(","));
-            String base = getBase(arguments);
+            String base;
+            List<String> baseArguments;
+            if (typedText.endsWith(",")) {
+                baseArguments = arguments;
+            } else {
+                baseArguments = arguments.subList(0, arguments.size() - 1);
+            }
+            base = String.join(",", baseArguments) + ",";
             String lastArgument = arguments.get(arguments.size() - 1);
 
             // Filter available values by the text after the last comma only
@@ -52,7 +59,7 @@ public final class TabCompletionHelper {
             // Remove any already used values
             List<String> unused = new ArrayList<>();
             for (String string : filtered) {
-                if (!arguments.contains(string)) {
+                if (!baseArguments.contains(string)) {
                     unused.add(base + string);
                 }
             }

src/test/java/net/knarcraft/knarlib/util/TabCompletionHelperTest.java

@@ -0,0 +1,48 @@
+package net.knarcraft.knarlib.util;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * Tests for the tab-completion helper
+ */
+public class TabCompletionHelperTest {
+
+    @Test
+    public void getStringListUnfilteredTest() {
+        List<String> input = List.of("a", "b", "c", "d");
+        List<String> result = TabCompletionHelper.getStringList(input, "a,b,", null);
+        List<String> expected = List.of("a,b,c", "a,b,d");
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void getStringListUnfilteredTest2() {
+        List<String> input = List.of("a", "b", "c", "d");
+        List<String> result = TabCompletionHelper.getStringList(input, "a,b", null);
+        List<String> expected = List.of("a,b", "a,c", "a,d");
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void getStringListContainsTest() {
+        List<String> input = List.of("ape", "ball", "car", "donut");
+        List<String> result = TabCompletionHelper.getStringList(input, "ball,donut,r",
+                TabCompletionHelper::filterMatchingContains);
+        List<String> expected = List.of("ball,donut,car");
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void getStringListStartsWithTest() {
+        List<String> input = List.of("ape", "ball", "car", "donut");
+        List<String> result = TabCompletionHelper.getStringList(input, "ball,donut,a",
+                TabCompletionHelper::filterMatchingStartsWith);
+        List<String> expected = List.of("ball,donut,ape");
+        assertEquals(expected, result);
+    }
+
+}