Fix C# Language Server (#262)

Now when the language server starts, the initialisation will scan for solution or project files, and then pass them to the language server instructing it to open them. Which in-turn should give us all the nice context since the code is actually being 'loaded' up properly now.

test/solidlsp/csharp/test_csharp_basic.py

@@ -1,9 +1,17 @@
 import os
+import tempfile
+from pathlib import Path
+from unittest.mock import Mock, patch
 
 import pytest
 
 from solidlsp import SolidLanguageServer
-from solidlsp.ls_config import Language
+from solidlsp.language_servers.csharp_language_server.csharp_language_server import (
+    CSharpLanguageServer,
+    breadth_first_file_scan,
+    find_solution_or_project_file,
+)
+from solidlsp.ls_config import Language, LanguageServerConfig
 from solidlsp.ls_utils import SymbolUtils
 
 
@@ -77,3 +85,181 @@ class TestCSharpLanguageServer:
         assert "Email" in symbol_names
         assert "ToString" in symbol_names
         assert "IsAdult" in symbol_names
+
+
+@pytest.mark.csharp
+class TestCSharpSolutionProjectOpening:
+    """Test C# language server solution and project opening functionality."""
+
+    def test_breadth_first_file_scan(self):
+        """Test that breadth_first_file_scan finds files in breadth-first order."""
+        with tempfile.TemporaryDirectory() as temp_dir:
+            temp_path = Path(temp_dir)
+
+            # Create test directory structure
+            (temp_path / "file1.txt").touch()
+            (temp_path / "subdir1").mkdir()
+            (temp_path / "subdir1" / "file2.txt").touch()
+            (temp_path / "subdir2").mkdir()
+            (temp_path / "subdir2" / "file3.txt").touch()
+            (temp_path / "subdir1" / "subdir3").mkdir()
+            (temp_path / "subdir1" / "subdir3" / "file4.txt").touch()
+
+            # Scan files
+            files = list(breadth_first_file_scan(str(temp_path)))
+            filenames = [os.path.basename(f) for f in files]
+
+            # Should find all files
+            assert len(files) == 4
+            assert "file1.txt" in filenames
+            assert "file2.txt" in filenames
+            assert "file3.txt" in filenames
+            assert "file4.txt" in filenames
+
+            # file1.txt should be found first (breadth-first)
+            assert filenames[0] == "file1.txt"
+
+    def test_find_solution_or_project_file_with_solution(self):
+        """Test that find_solution_or_project_file prefers .sln files."""
+        with tempfile.TemporaryDirectory() as temp_dir:
+            temp_path = Path(temp_dir)
+
+            # Create both .sln and .csproj files
+            solution_file = temp_path / "MySolution.sln"
+            project_file = temp_path / "MyProject.csproj"
+            solution_file.touch()
+            project_file.touch()
+
+            result = find_solution_or_project_file(str(temp_path))
+
+            # Should prefer .sln file
+            assert result == str(solution_file)
+
+    def test_find_solution_or_project_file_with_project_only(self):
+        """Test that find_solution_or_project_file falls back to .csproj files."""
+        with tempfile.TemporaryDirectory() as temp_dir:
+            temp_path = Path(temp_dir)
+
+            # Create only .csproj file
+            project_file = temp_path / "MyProject.csproj"
+            project_file.touch()
+
+            result = find_solution_or_project_file(str(temp_path))
+
+            # Should return .csproj file
+            assert result == str(project_file)
+
+    def test_find_solution_or_project_file_with_nested_files(self):
+        """Test that find_solution_or_project_file finds files in subdirectories."""
+        with tempfile.TemporaryDirectory() as temp_dir:
+            temp_path = Path(temp_dir)
+
+            # Create nested structure
+            (temp_path / "src").mkdir()
+            solution_file = temp_path / "src" / "MySolution.sln"
+            solution_file.touch()
+
+            result = find_solution_or_project_file(str(temp_path))
+
+            # Should find nested .sln file
+            assert result == str(solution_file)
+
+    def test_find_solution_or_project_file_returns_none_when_no_files(self):
+        """Test that find_solution_or_project_file returns None when no .sln or .csproj files exist."""
+        with tempfile.TemporaryDirectory() as temp_dir:
+            temp_path = Path(temp_dir)
+
+            # Create some other files
+            (temp_path / "readme.txt").touch()
+            (temp_path / "other.cs").touch()
+
+            result = find_solution_or_project_file(str(temp_path))
+
+            # Should return None
+            assert result is None
+
+    def test_find_solution_or_project_file_prefers_solution_breadth_first(self):
+        """Test that solution files are preferred even when deeper in the tree."""
+        with tempfile.TemporaryDirectory() as temp_dir:
+            temp_path = Path(temp_dir)
+
+            # Create .csproj at root and .sln in subdirectory
+            project_file = temp_path / "MyProject.csproj"
+            project_file.touch()
+
+            (temp_path / "src").mkdir()
+            solution_file = temp_path / "src" / "MySolution.sln"
+            solution_file.touch()
+
+            result = find_solution_or_project_file(str(temp_path))
+
+            # Should still prefer .sln file even though it's deeper
+            assert result == str(solution_file)
+
+    @patch("solidlsp.language_servers.csharp_language_server.csharp_language_server.CSharpLanguageServer._ensure_server_installed")
+    @patch("solidlsp.language_servers.csharp_language_server.csharp_language_server.CSharpLanguageServer._start_server")
+    def test_csharp_language_server_logs_solution_discovery(self, mock_start_server, mock_ensure_server_installed):
+        """Test that CSharpLanguageServer logs solution/project discovery during initialization."""
+        with tempfile.TemporaryDirectory() as cache_dir:
+            # Mock the server installation
+            mock_ensure_server_installed.return_value = ("/usr/bin/dotnet", "/path/to/server.dll", Path(cache_dir))
+
+            # Create test directory with solution file
+            with tempfile.TemporaryDirectory() as temp_dir:
+                temp_path = Path(temp_dir)
+                solution_file = temp_path / "TestSolution.sln"
+                solution_file.touch()
+
+                # Mock logger to capture log messages
+                mock_logger = Mock()
+                mock_config = Mock(spec=LanguageServerConfig)
+                mock_config.ignored_paths = []
+
+                # Create CSharpLanguageServer instance
+                CSharpLanguageServer(mock_config, mock_logger, str(temp_path))
+
+                # Verify that logger was called with solution file discovery
+                mock_logger.log.assert_any_call(f"Found solution/project file: {solution_file}", 20)  # logging.INFO
+
+    @patch("solidlsp.language_servers.csharp_language_server.csharp_language_server.CSharpLanguageServer._ensure_server_installed")
+    @patch("solidlsp.language_servers.csharp_language_server.csharp_language_server.CSharpLanguageServer._start_server")
+    def test_csharp_language_server_logs_no_solution_warning(self, mock_start_server, mock_ensure_server_installed):
+        """Test that CSharpLanguageServer logs warning when no solution/project files are found."""
+        with tempfile.TemporaryDirectory() as cache_dir:
+            # Mock the server installation
+            mock_ensure_server_installed.return_value = ("/usr/bin/dotnet", "/path/to/server.dll", Path(cache_dir))
+
+            # Create empty test directory
+            with tempfile.TemporaryDirectory() as temp_dir:
+                temp_path = Path(temp_dir)
+
+                # Mock logger to capture log messages
+                mock_logger = Mock()
+                mock_config = Mock(spec=LanguageServerConfig)
+                mock_config.ignored_paths = []
+
+                # Create CSharpLanguageServer instance
+                CSharpLanguageServer(mock_config, mock_logger, str(temp_path))
+
+                # Verify that logger was called with warning about no solution/project files
+                mock_logger.log.assert_any_call(
+                    "No .sln or .csproj file found, language server will attempt auto-discovery", 30  # logging.WARNING
+                )
+
+    def test_solution_and_project_opening_with_real_test_repo(self):
+        """Test solution and project opening with the actual C# test repository."""
+        # Get the C# test repo path
+        test_repo_path = Path(__file__).parent.parent.parent / "resources" / "repos" / "csharp" / "test_repo"
+
+        if not test_repo_path.exists():
+            pytest.skip("C# test repository not found")
+
+        # Test solution/project discovery in the real test repo
+        result = find_solution_or_project_file(str(test_repo_path))
+
+        # Should find either .sln or .csproj file
+        assert result is not None
+        assert result.endswith((".sln", ".csproj"))
+
+        # Verify the file actually exists
+        assert os.path.exists(result)