Add unit tests for FileSystem class and enhance ReadAllTextAsync for concurrent access

Michael Pawlik · Michael Pawlik · commit d1bd9ef95ca2 · 2026-01-12T14:53:52.000+01:00
diff --git a/Calinga.NET.Tests/FileSystemTests.cs b/Calinga.NET.Tests/FileSystemTests.cs
@@ -0,0 +1,117 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using Calinga.NET.Infrastructure;
+using FluentAssertions;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Calinga.NET.Tests
+{
+    [TestClass]
+    public class FileSystemTests
+    {
+        private string _tempDir;
+        private FileSystem _sut;
+
+        [TestInitialize]
+        public void Init()
+        {
+            _tempDir = Path.Combine(Path.GetTempPath(), $"FileSystemTest_{Guid.NewGuid()}");
+            Directory.CreateDirectory(_tempDir);
+            _sut = new FileSystem();
+        }
+
+        [TestCleanup]
+        public void Cleanup()
+        {
+            if (Directory.Exists(_tempDir))
+                Directory.Delete(_tempDir, true);
+        }
+
+        [TestMethod]
+        public async Task ReadAllTextAsync_ShouldAllowConcurrentReads()
+        {
+            // Arrange
+            var filePath = Path.Combine(_tempDir, "test.json");
+            var content = "{\"key\": \"value\"}";
+            await File.WriteAllTextAsync(filePath, content);
+
+            // Act - Multiple concurrent reads should not throw
+            var tasks = Enumerable.Range(0, 10)
+                .Select(_ => Task.Run(() => _sut.ReadAllTextAsync(filePath)))
+                .ToList();
+
+            Func<Task> act = async () => await Task.WhenAll(tasks);
+
+            // Assert
+            await act.Should().NotThrowAsync("concurrent reads should be allowed");
+
+            // Verify all reads returned correct content
+            var results = await Task.WhenAll(tasks);
+            foreach (var result in results)
+            {
+                result.Should().Be(content);
+            }
+        }
+
+        [TestMethod]
+        public async Task WriteAllTextAsync_ShouldCreateFileWithContent()
+        {
+            // Arrange
+            var filePath = Path.Combine(_tempDir, "write_test.json");
+            var content = "{\"test\": \"data\"}";
+
+            // Act
+            await _sut.WriteAllTextAsync(filePath, content);
+
+            // Assert
+            File.Exists(filePath).Should().BeTrue();
+            var readContent = await File.ReadAllTextAsync(filePath);
+            readContent.Should().Be(content);
+        }
+
+        [TestMethod]
+        public async Task ReadAllTextAsync_ShouldReadFileContent()
+        {
+            // Arrange
+            var filePath = Path.Combine(_tempDir, "read_test.json");
+            var content = "{\"hello\": \"world\"}";
+            await File.WriteAllTextAsync(filePath, content);
+
+            // Act
+            var result = await _sut.ReadAllTextAsync(filePath);
+
+            // Assert
+            result.Should().Be(content);
+        }
+
+        [TestMethod]
+        public void FileExists_ShouldReturnTrue_WhenFileExists()
+        {
+            // Arrange
+            var filePath = Path.Combine(_tempDir, "exists_test.json");
+            File.WriteAllText(filePath, "test");
+
+            // Act
+            var result = _sut.FileExists(filePath);
+
+            // Assert
+            result.Should().BeTrue();
+        }
+
+        [TestMethod]
+        public void FileExists_ShouldReturnFalse_WhenFileDoesNotExist()
+        {
+            // Arrange
+            var filePath = Path.Combine(_tempDir, "nonexistent.json");
+
+            // Act
+            var result = _sut.FileExists(filePath);
+
+            // Assert
+            result.Should().BeFalse();
+        }
+    }
+}
diff --git a/Calinga.NET/Infrastructure/FileSystem.cs b/Calinga.NET/Infrastructure/FileSystem.cs
@@ -21,7 +21,7 @@ public async Task WriteAllTextAsync(string path, string contents)
 
         public async Task<string> ReadAllTextAsync(string path)
         {
-            using (var tempFileStream = new FileStream(path, FileMode.Open, FileAccess.Read))
+            using (var tempFileStream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
             using (var tempStreamReader = new StreamReader(tempFileStream, Encoding.UTF8))
             {
                 return await tempStreamReader.ReadToEndAsync().ConfigureAwait(false);

Original file line number	Diff line number	Diff line change
`@@ -21,7 +21,7 @@ public async Task WriteAllTextAsync(string path, string contents)`
`21`	`21`
`22`	`22`	`public async Task<string> ReadAllTextAsync(string path)`
`23`	`23`	`{`
`24`		`- using (var tempFileStream = new FileStream(path, FileMode.Open, FileAccess.Read))`
	`24`	`+ using (var tempFileStream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))`
`25`	`25`	`using (var tempStreamReader = new StreamReader(tempFileStream, Encoding.UTF8))`
`26`	`26`	`{`
`27`	`27`	`return await tempStreamReader.ReadToEndAsync().ConfigureAwait(false);`