using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;

using NUnit.Framework;

using Python.Runtime;
using Python.Test;

namespace Python.PythonTestsRunner
{
 public class PythonTestRunner
 {
 [OneTimeSetUp]
 public void SetUp()
 {
 PythonEngine.Initialize();
 }

 [OneTimeTearDown]
 public void Dispose()
 {
 PythonEngine.Shutdown();
 }

 /// <summary>
 /// Selects the Python tests to be run as embedded tests.
 /// </summary>
 /// <returns></returns>
 static IEnumerable<string[]> PythonTestCases()
 {
 // Add the test that you want to debug here.
 yield return new[] { "test_indexer", "test_boolean_indexer" };
 yield return new[] { "test_delegate", "test_bool_delegate" };
 yield return new[] { "test_subclass", "test_implement_interface_and_class" };
 }

 /// <summary>
 /// Runs a test in src/tests/*.py as an embedded test. This facilitates debugging.
 /// </summary>
 /// <param name="testFile">The file name without extension</param>
 /// <param name="testName">The name of the test method</param>
 [TestCaseSource(nameof(PythonTestCases))]
 public void RunPythonTest(string testFile, string testName)
 {
 // Find the tests directory
 string folder = typeof(PythonTestRunner).Assembly.Location;
 while (Path.GetFileName(folder) != "src")
 {
 folder = Path.GetDirectoryName(folder);
 }
 folder = Path.Combine(folder, "..", "tests");
 string path = Path.Combine(folder, testFile + ".py");
 if (!File.Exists(path)) throw new FileNotFoundException("Cannot find test file", path);

 // We could use 'import' below, but importlib gives more helpful error messages than 'import'
 // https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
 // Because the Python tests sometimes have relative imports, the module name must be inside the tests package
 PythonEngine.Exec($@"
import sys
import os
sys.path.append(os.path.dirname(r'{folder}'))
sys.path.append(os.path.join(r'{folder}', 'fixtures'))
import clr
clr.AddReference('Python.Test')
import tests
module_name = 'tests.{testFile}'
file_path = r'{path}'
import importlib.util
spec = importlib.util.spec_from_file_location(module_name, file_path)
module = importlib.util.module_from_spec(spec)
sys.modules[module_name] = module
try:
 spec.loader.exec_module(module)
except ImportError as error:
 raise ImportError(str(error) + ' when sys.path=' + os.pathsep.join(sys.path))
module.{testName}()
");
 }
 }
}