Fix null/undefined lyrics which cause exporter to fail

src.csharp/AlphaTab.Test/Test/Globals.cs

@@ -87,7 +87,14 @@ public void ToBeTrue()
 
         public void ToBeFalsy()
         {
-            Assert.AreEqual(default!, _actual, _message);
+            if (_actual is string s) 
+            {
+                Assert.IsTrue(string.IsNullOrEmpty(s), _message);
+            }
+            else 
+            {
+                Assert.AreEqual(default!, _actual, _message);
+            }
         }
 
         public void ToThrowError(Type expected)

src.kotlin/alphaTab/alphaTab/src/androidTest/kotlin/alphaTab/test/Globals.kt

@@ -68,7 +68,12 @@ public class Expector<T> {
     }
 
     public fun toBeFalsy() {
-        kotlin.test.assertNull(_actual, _message)
+        val actual = _actual;
+        if(actual is String){
+            kotlin.test.assertTrue(actual.isEmpty(), _message)
+        } else {
+            kotlin.test.assertNull(_actual, _message)
+        }
     }
 
     public fun toThrowError(expected: KClass<out Exception>) {

src.kotlin/alphaTab/alphaTab/src/commonMain/kotlin/alphaTab/collections/List.kt

@@ -39,6 +39,10 @@ public class List<T> : Iterable<T> {
         _data.add(item)
     }
 
+    public fun fill(item: T) {
+        _data.fill(item)
+    }
+
     public fun push(items: List<T>) {
         _data.addAll(items._data)
     }

src/model/Track.ts

@@ -102,6 +102,7 @@ export class Track {
                         // initialize lyrics list for beat if required
                         if (!beat.lyrics) {
                             beat.lyrics = new Array<string>(lyrics.length);
+                            beat.lyrics.fill("");
                         }
                         // assign chunk
                         beat.lyrics[li] = lyric.chunks[ci];

test/exporter/Gp7Exporter.test.ts

@@ -14,8 +14,7 @@ describe('Gp7ExporterTest', () => {
         const data = await TestPlatform.loadFile('test-data/' + name);
         try {
             return ScoreLoader.loadScoreFromBytes(data);
-        }
-        catch (e) {
+        } catch (e) {
             return null;
         }
     };
@@ -30,7 +29,10 @@ describe('Gp7ExporterTest', () => {
         return new Gp7Exporter().export(score, null);
     };
 
-    const testRoundTripEqual: (name: string, ignoreKeys: string[] | null) => Promise<void> = async (name: string, ignoreKeys: string[] | null = null): Promise<void> => {
+    const testRoundTripEqual: (name: string, ignoreKeys: string[] | null) => Promise<void> = async (
+        name: string,
+        ignoreKeys: string[] | null = null
+    ): Promise<void> => {
         try {
             const expected = await loadScore(name);
             if (!expected) {
@@ -42,7 +44,7 @@ describe('Gp7ExporterTest', () => {
             const actual = prepareGp7ImporterWithBytes(exported).readScore();
 
             const expectedJson = JsonConverter.scoreToJsObject(expected);
-            const actualJson = JsonConverter.scoreToJsObject(actual)
+            const actualJson = JsonConverter.scoreToJsObject(actual);
 
             if (!ComparisonHelpers.expectJsonEqual(expectedJson, actualJson, '<' + fileName + '>', ignoreKeys)) {
                 await TestPlatform.saveFile(fileName, exported);
@@ -109,7 +111,7 @@ describe('Gp7ExporterTest', () => {
         await testRoundTripEqual(`conversion/full-song.gpx`, [
             'accidentalmode', // gets upgraded from default
             'percussionarticulations', // gets added
-            'percussionarticulation', // gets added
+            'percussionarticulation' // gets added
         ]);
     });
 
@@ -136,8 +138,12 @@ describe('Gp7ExporterTest', () => {
         const actual = prepareGp7ImporterWithBytes(exported).readScore();
 
         const expectedJson = JsonConverter.scoreToJsObject(expected);
-        const actualJson = JsonConverter.scoreToJsObject(actual)
+        const actualJson = JsonConverter.scoreToJsObject(actual);
 
         ComparisonHelpers.expectJsonEqual(expectedJson, actualJson, '<alphatex>', ['accidentalmode']);
     });
+
+    it('gp7-lyrics-null', async () => {
+        await testRoundTripEqual('guitarpro7/lyrics-null.gp', null);
+    });
 });