em 01: scaffold ExtractMethod tool + Demo fixture

- tools/ExtractMethod: net10.0 console app (Microsoft.CodeAnalysis.CSharp 5.9.0, pinned latest stable). CLI: <file.cs> <startLine> <endLine>. Parses the file, builds a scratch compilation with refs from TRUSTED_PLATFORM_ASSEMBLIES, and reports how many whole statements the line range covers (clean error otherwise; exit codes: 0 ok, 1 resolution error, 2 usage). - Tooling/CompilationLoader: shared parse + compilation path for CLI and tests (tests exercise the exact loading path the CLI uses). - Tooling/SelectionResolver: snaps a 1-based inclusive line range to whole statements in the enclosing method body block; boundary checks never split a statement; nested/blank-line ranges handled cleanly. - tests/: ExtractMethod/Fixtures/Demo.cs checked-in fixture exercising every bucket of the parent spec (read-only local, written+read-later return, scratch local, param read, field+property access, indexer + method invocation, multi-statement range incl. a for-loop); excluded from project compilation, copied to output as data. - Tests: Demo.cs compiles with no diagnostics; range 68..72 resolves to 2 statements (LocalDeclarationStatement, ForStatement); AnalyzeDataFlow succeeds on the fixture's for-loop node; mid-statement range fails cleanly. 30/30 green.
2026-09-12 15:28:14 +01:00
parent 406e8a97f6
commit b012d0aaa0
9 changed files with 526 additions and 1 deletions
@@ -0,0 +1,102 @@
+using ExtractMethod.Tooling;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace BeforeAfter.Tests.ExtractMethod;
+
+/// <summary>
+/// Tests for yak em 01: the scaffold (console tool) and the checked-in demo
+/// fixture. The fixture is DATA (excluded from compilation, copied to the
+/// output dir), and it is parsed with the tool's own <see cref="CompilationLoader"/>
+/// so these tests exercise the exact loading path the CLI uses.
+/// </summary>
+public class DemoFixtureTests
+{
+    private static readonly string FixturePath =
+        Path.Combine(AppContext.BaseDirectory, "Fixtures", "Demo.cs");
+
+    private static (SyntaxTree Tree, CSharpCompilation Compilation) LoadFixture()
+    {
+        Assert.True(File.Exists(FixturePath), $"fixture missing at {FixturePath}");
+        var tree = CompilationLoader.ParseFile(FixturePath);
+        var compilation = CompilationLoader.CreateCompilation(tree, "DemoFixture");
+        return (tree, compilation);
+    }
+
+    // ---------------------------------------------------------------------
+    // (a) The fixture is pristine under the scratch compilation: if this
+    //     fails, the fixture (or the TRUSTED_PLATFORM_ASSEMBLIES reference
+    //     loading) is broken and every later yak would analyze garbage.
+    // ---------------------------------------------------------------------
+    [Fact]
+    public void Demo_compiles_with_no_diagnostics()
+    {
+        var (_, compilation) = LoadFixture();
+
+        Assert.Empty(compilation.GetDiagnostics());
+    }
+
+    // ---------------------------------------------------------------------
+    // (b) A known line range snaps to the expected whole statements.
+    //     Lines 68..72 of Demo.cs are `int total = 0;` followed by the whole
+    //     for-loop (for keyword .. closing brace) inside Summarize — exactly
+    //     the "multi-statement range incl. a for-loop" shape of the spec.
+    // ---------------------------------------------------------------------
+    [Fact]
+    public void Known_range_resolves_to_expected_statements()
+    {
+        var (tree, _) = LoadFixture();
+
+        var report = SelectionResolver.Resolve(tree, 68, 72);
+
+        Assert.True(report.Succeeded, report.Error);
+        Assert.Equal(2, report.Count);
+        Assert.Equal(
+            new[] { SyntaxKind.LocalDeclarationStatement, SyntaxKind.ForStatement },
+            report.Kinds);
+        Assert.Equal("Summarize", report.Method?.Identifier.ValueText);
+    }
+
+    // ---------------------------------------------------------------------
+    // (c) The semantic model's data-flow analysis works on the fixture's
+    //     for-loop node — the foundation every classification in yak 02
+    //     builds on. (AnalyzeDataFlow on the loop itself walks the bound loop
+    //     body; Succeeded == false would mean the scratch compilation or the
+    //     selected node cannot be bound.)
+    // ---------------------------------------------------------------------
+    [Fact]
+    public void Fixture_for_loop_supports_data_flow_analysis()
+    {
+        var (tree, compilation) = LoadFixture();
+
+        var forStatement = tree.GetRoot()
+            .DescendantNodes()
+            .OfType<ForStatementSyntax>()
+            .Single(n => EnclosingMethodName(n) == "Summarize");
+
+        var dataFlow = compilation.GetSemanticModel(tree).AnalyzeDataFlow(forStatement);
+
+        Assert.True(dataFlow.Succeeded);
+    }
+
+    // ---------------------------------------------------------------------
+    // Acceptance also demands "clean error otherwise": selecting only the
+    // for-loop header line (line 69) splits the statement and must fail with
+    // a readable reason instead of a crash or a silent wrong count.
+    // ---------------------------------------------------------------------
+    [Fact]
+    public void Range_ending_mid_statement_fails_cleanly()
+    {
+        var (tree, _) = LoadFixture();
+
+        var report = SelectionResolver.Resolve(tree, 69, 69);
+
+        Assert.False(report.Succeeded);
+        Assert.NotNull(report.Error);
+        Assert.Contains("no whole", report.Error);
+    }
+
+    private static string? EnclosingMethodName(SyntaxNode node) =>
+        node.AncestorsAndSelf().OfType<MethodDeclarationSyntax>().FirstOrDefault()?.Identifier.ValueText;
+}