Capture trace warnings from libpalaso verse and chapter parsing

src/Machine/src/Serval.Machine.Shared/Services/PreprocessBuildJob.cs

@@ -1,4 +1,6 @@
-namespace Serval.Machine.Shared.Services;
+using Trace = System.Diagnostics.Trace;
+
+namespace Serval.Machine.Shared.Services;
 
 public abstract class PreprocessBuildJob<TEngine>(
     IPlatformService platformService,
@@ -139,21 +141,34 @@ IReadOnlyList<ParallelCorpus> corpora
     {
         List<string> warnings = [];
 
-        foreach (ParallelCorpus parallelCorpus in corpora)
+        // Listen to the trace messages from libpalaso, and record them as warnings
+        var listener = new WarningsTraceListener(warnings, "USFM Parsing error: ");
+        try
         {
-            IReadOnlyList<(string MonolingualCorpusId, IReadOnlyList<UsfmVersificationError> errors)> errorsPerCorpus =
-                ParallelCorpusPreprocessingService.AnalyzeUsfmVersification(parallelCorpus);
-
-            foreach ((string monolingualCorpusId, IReadOnlyList<UsfmVersificationError> errors) in errorsPerCorpus)
+            Trace.Listeners.Add(listener);
+            foreach (ParallelCorpus parallelCorpus in corpora)
             {
-                foreach (UsfmVersificationError error in errors)
+                IReadOnlyList<(
+                    string MonolingualCorpusId,
+                    IReadOnlyList<UsfmVersificationError> errors
+                )> errorsPerCorpus = ParallelCorpusPreprocessingService.AnalyzeUsfmVersification(parallelCorpus);
+
+                foreach ((string monolingualCorpusId, IReadOnlyList<UsfmVersificationError> errors) in errorsPerCorpus)
                 {
-                    warnings.Add(
-                        $"USFM versification error in project {error.ProjectName}, expected verse “{error.ExpectedVerseRef}”, actual verse “{error.ActualVerseRef}”, mismatch type {error.Type} (parallel corpus {parallelCorpus.Id}, monolingual corpus {monolingualCorpusId})"
-                    );
+                    foreach (UsfmVersificationError error in errors)
+                    {
+                        warnings.Add(
+                            $"USFM versification error in project {error.ProjectName}, expected verse “{error.ExpectedVerseRef}”, actual verse “{error.ActualVerseRef}”, mismatch type {error.Type} (parallel corpus {parallelCorpus.Id}, monolingual corpus {monolingualCorpusId})"
+                        );
+                    }
                 }
             }
         }
+        finally
+        {
+            Trace.Listeners.Remove(listener);
+        }
+
         return warnings;
     }
 }

src/Machine/src/Serval.Machine.Shared/Services/WarningsTraceListener.cs

@@ -0,0 +1,12 @@
+namespace Serval.Machine.Shared.Services;
+
+public class WarningsTraceListener(List<string> outputList, string prefix = "") : TraceListener
+{
+    public override void Write(string? message) { }
+
+    public override void WriteLine(string? message)
+    {
+        if (!string.IsNullOrWhiteSpace(message))
+            outputList.Add(prefix + message);
+    }
+}

src/Machine/test/Serval.Machine.Shared.Tests/Services/WarningsTraceListenerTests.cs

@@ -0,0 +1,61 @@
+namespace Serval.Machine.Shared.Services;
+
+[TestFixture]
+public class WarningsTraceListenerTests
+{
+    [Test]
+    public void CapturesChapterParsingWarnings()
+    {
+        using var testEnvironment = new TestEnvironment();
+        const string Chapter = "1.";
+
+        var verseRef = new VerseRef { Chapter = Chapter };
+        Assert.Multiple(() =>
+        {
+            Assert.That(verseRef.Chapter, Is.Empty);
+            Assert.That(testEnvironment.Warnings, Has.Count.EqualTo(1));
+            Assert.That(
+                testEnvironment.Warnings[0],
+                Is.EqualTo(testEnvironment.Prefix + "Just failed to parse a chapter number: " + Chapter)
+            );
+        });
+    }
+
+    [Test]
+    public void CapturesVerseParsingWarnings()
+    {
+        using var testEnvironment = new TestEnvironment();
+        const string Verse = "v1";
+
+        var verseRef = new VerseRef { Verse = Verse };
+        Assert.Multiple(() =>
+        {
+            Assert.That(verseRef.Chapter, Is.EqualTo("0"));
+            Assert.That(testEnvironment.Warnings, Has.Count.EqualTo(1));
+            Assert.That(
+                testEnvironment.Warnings[0],
+                Is.EqualTo(testEnvironment.Prefix + "Just failed to parse a verse number: " + Verse)
+            );
+        });
+    }
+
+    public class TestEnvironment : DisposableBase
+    {
+        private readonly WarningsTraceListener _listener;
+
+        public TestEnvironment()
+        {
+            _listener = new WarningsTraceListener(Warnings, Prefix);
+            Trace.Listeners.Add(_listener);
+        }
+
+        public string Prefix { get; } = "USFM Parsing error: ";
+        public List<string> Warnings { get; } = [];
+
+        protected override void DisposeManagedResources()
+        {
+            Trace.Listeners.Remove(_listener);
+            _listener.Dispose();
+        }
+    }
+}

src/Machine/test/Serval.Machine.Shared.Tests/Usings.cs

@@ -1,4 +1,5 @@
 global using System.Collections;
+global using System.Diagnostics;
 global using System.IO.Compression;
 global using System.Text.Json;
 global using System.Text.Json.Nodes;