hrynco-common/HrynCo.Common.Tests/TimeApiUsageGuardTests.cs

namespace HrynCo.Common.Tests;

using FluentAssertions;
using Xunit;

public sealed class TimeApiUsageGuardTests
{
    private static readonly string[] ForbiddenPatterns =
    [
        "DateTime.Now",
        "DateTimeOffset.Now"
    ];

    [Fact]
    public void ProductionCode_ShouldNotUseLocalNowApis()
    {
        string solutionRoot = GetSolutionRoot();

        var violations = Directory
            .EnumerateFiles(solutionRoot, "*.cs", SearchOption.AllDirectories)
            .Where(IsProductionSourceFile)
            .SelectMany(file => FindViolations(solutionRoot, file))
            .ToArray();

        violations.Should().BeEmpty(
            "production code should use UTC-based APIs for persisted and serialized timestamps.{0}{1}",
            Environment.NewLine,
            string.Join(Environment.NewLine, violations));
    }

    private static string GetSolutionRoot()
    {
        string? current = AppContext.BaseDirectory;

        while (current is not null)
        {
            if (File.Exists(Path.Combine(current, "HrynCo.Common.sln")))
            {
                return current;
            }

            current = Directory.GetParent(current)?.FullName;
        }

        throw new DirectoryNotFoundException("Could not locate the solution root from the test assembly output.");
    }

    private static bool IsProductionSourceFile(string filePath)
    {
        string normalizedPath = filePath.Replace('\\', '/');

        return !normalizedPath.Contains("/bin/", StringComparison.OrdinalIgnoreCase)
               && !normalizedPath.Contains("/obj/", StringComparison.OrdinalIgnoreCase)
               && !normalizedPath.Contains("/Migrations/", StringComparison.OrdinalIgnoreCase)
               && !normalizedPath.Contains(".Tests/", StringComparison.OrdinalIgnoreCase)
               && !normalizedPath.Contains(".IntegrationTests/", StringComparison.OrdinalIgnoreCase);
    }

    private static IEnumerable<string> FindViolations(string solutionRoot, string filePath)
    {
        string relativePath = Path.GetRelativePath(solutionRoot, filePath).Replace('\\', '/');
        string[] lines = File.ReadAllLines(filePath);

        for (int lineIndex = 0; lineIndex < lines.Length; lineIndex++)
        {
            string line = lines[lineIndex];

            foreach (string forbiddenPattern in ForbiddenPatterns)
            {
                if (line.Contains(forbiddenPattern, StringComparison.Ordinal))
                {
                    yield return $"{relativePath}:{lineIndex + 1} contains forbidden API `{forbiddenPattern}`";
                }
            }
        }
    }
}