Fix hint name when root namespace is empty

Author: atifaziz

src/DocoptNet/CodeGeneration/SourceGenerator.cs

@@ -166,7 +166,7 @@ public void Execute(GeneratorExecutionContext context)
                     if (Generate(ns, name, parentNames, attribute?.HelpConstName, help, options) is { Length: > 0 } source)
                     {
                         hintNameBuilder.Clear();
-                        if (ns is { } someNamespace)
+                        if (ns?.Trim() is { Length: > 0 } someNamespace)
                             hintNameBuilder.Append(someNamespace).Append('.');
                         if (parentNames.Length > 0)
                         {

tests/DocoptNet.Tests/CodeGeneration/SourceGeneratorTests.cs

@@ -54,6 +54,17 @@ public void Generate_with_usage_in_external_file()
             });
         }
 
+        [Test]
+        public void Generate_with_empty_root_namespace()
+        {
+            AssertMatchesSnapshot(
+                analyzerConfigOptions: new(KeyValuePair.Create("build_property.RootNamespace", string.Empty)),
+                sources: new[]
+            {
+                ("Program.docopt.txt", SourceText.From(NavalFateUsage))
+            });
+        }
+
         [Test]
         public void Generate_with_inline_usage()
         {
@@ -256,9 +267,10 @@ sealed partial class ProgramArguments
         }
 
         void AssertMatchesSnapshot((string Path, SourceText Text)[] sources,
+                                   AnalyzerConfigOptions? analyzerConfigOptions = null,
                                    [CallerMemberName]string? callerName = null)
         {
-            var (driver, compilation) = PrepareForGeneration(sources);
+            var (driver, compilation) = PrepareForGeneration(analyzerConfigOptions ?? new(), sources);
 
             var grr = driver.RunGeneratorsAndUpdateCompilation(compilation, out var outputCompilation, out _)
                             .GetRunResult().Results.Single();
@@ -340,7 +352,16 @@ where Path.GetFileName(fp) is { } fn
                        || fn.EndsWith(".json", StringComparison.OrdinalIgnoreCase))
                 select Path.GetRelativePath(solutionDirPath, fp);
 
-            var actualFiles = EnumerateFiles(actualSourcesPath);
+            var actualFiles = EnumerateFiles(actualSourcesPath).ToImmutableArray();
+
+            Assert.That(from gs in grr.GeneratedSources
+                        orderby gs.HintName
+                        select gs.HintName,
+                        Is.EqualTo(from af in actualFiles
+                                   select Path.GetFileName(af) into af
+                                   where af.EndsWith(".cs", StringComparison.OrdinalIgnoreCase)
+                                   orderby af
+                                   select af));
 
             var expectedFiles = Directory.Exists(expectedSourcesPath)
                               ? EnumerateFiles(expectedSourcesPath)
@@ -553,7 +574,12 @@ public partial class " + ProgramArgumentsClassName + @" { }
             new AnalyzerConfigOptions(KeyValuePair.Create("build_metadata.AdditionalFiles.SourceItemType", "Docopt"));
 
         internal static (CSharpGeneratorDriver, CSharpCompilation)
-            PrepareForGeneration(params (string Path, SourceText Text)[] sources)
+            PrepareForGeneration(params (string Path, SourceText Text)[] sources) =>
+            PrepareForGeneration(new AnalyzerConfigOptions(), sources);
+
+        internal static (CSharpGeneratorDriver, CSharpCompilation)
+            PrepareForGeneration(AnalyzerConfigOptions analyzerConfigOptions,
+                                 params (string Path, SourceText Text)[] sources)
         {
             var trees = new List<SyntaxTree>();
             var additionalTexts = new List<AdditionalText>();
@@ -579,11 +605,9 @@ internal static (CSharpGeneratorDriver, CSharpCompilation)
 
             ISourceGenerator generator = new SourceGenerator();
 
-            var globalOptions = Enumerable.Empty<KeyValuePair<string, string>>();
-
             var optionsProvider =
                 new AnalyzerConfigOptionsProvider(
-                    new AnalyzerConfigOptions(globalOptions),
+                    analyzerConfigOptions,
                     additionalTexts.Select(at => KeyValuePair.Create(at, DocoptSourceItemTypeConfigOption))
                                    .ToImmutableDictionary());