Use correct filename for custom stylesheet

Author: ddaspit

src/SIL.Machine/Corpora/FileParatextProjectSettingsParser.cs

@@ -14,7 +14,7 @@ public FileParatextProjectSettingsParser(string projectDir)
 
         protected override UsfmStylesheet CreateStylesheet(string fileName)
         {
-            string customStylesheetFileName = Path.Combine(_projectDir, fileName);
+            string customStylesheetFileName = Path.Combine(_projectDir, "custom.sty");
             return new UsfmStylesheet(
                 fileName,
                 File.Exists(customStylesheetFileName) ? customStylesheetFileName : null

tests/SIL.Machine.Tests/Corpora/FileParatextProjectSettingsParserTests.cs

@@ -0,0 +1,16 @@
+using NUnit.Framework;
+
+namespace SIL.Machine.Corpora;
+
+public class FileParatextProjectSettingsParserTests
+{
+    [Test]
+    public void Parse_CustomStylesheet()
+    {
+        FileParatextProjectSettingsParser parser = new(CorporaTestHelpers.UsfmTestProjectPath);
+        ParatextProjectSettings settings = parser.Parse();
+        UsfmTag testTag = settings.Stylesheet.GetTag("test");
+        Assert.That(testTag.StyleType, Is.EqualTo(UsfmStyleType.Character));
+        Assert.That(testTag.TextType, Is.EqualTo(UsfmTextType.Other));
+    }
+}

tests/SIL.Machine.Tests/Corpora/TestData/usfm/Tes/custom.sty

@@ -0,0 +1,4 @@
+\Marker test
+\Endmarker test*
+\TextType Other
+\StyleType Character