Added strict mode to Cookie Crumble (#8126)

Author: glen-84

src/CookieCrumble/src/CookieCrumble/Snapshot.cs

@@ -242,6 +242,7 @@ public async ValueTask MatchAsync(CancellationToken cancellationToken = default)
 
         if (!File.Exists(snapshotFile))
         {
+            CheckStrictMode();
             EnsureDirectoryExists(snapshotFile);
             await using var stream = File.Create(snapshotFile);
             await stream.WriteAsync(writer.WrittenMemory, cancellationToken);
@@ -274,6 +275,7 @@ public void Match()
 
         if (!File.Exists(snapshotFile))
         {
+            CheckStrictMode();
             EnsureDirectoryExists(snapshotFile);
             using var stream = File.Create(snapshotFile);
             stream.Write(writer.WrittenSpan);
@@ -309,6 +311,7 @@ public async ValueTask MatchMarkdownAsync(CancellationToken cancellationToken =
 
         if (!File.Exists(snapshotFile))
         {
+            CheckStrictMode();
             EnsureDirectoryExists(snapshotFile);
             await using var stream = File.Create(snapshotFile);
             await stream.WriteAsync(writer.WrittenMemory, cancellationToken);
@@ -346,6 +349,7 @@ public void MatchMarkdown()
 
         if (!File.Exists(snapshotFile))
         {
+            CheckStrictMode();
             EnsureDirectoryExists(snapshotFile);
             using var stream = File.Create(snapshotFile);
             stream.Write(writer.WrittenSpan);
@@ -720,6 +724,20 @@ from methodInfo in classDeclaringType.GetMethods()
         return actualMethodInfo;
     }
 
+    private static void CheckStrictMode()
+    {
+        var value = Environment.GetEnvironmentVariable("COOKIE_CRUMBLE_STRICT_MODE");
+
+        if (string.Equals(value, "on", StringComparison.Ordinal)
+            || (bool.TryParse(value, out var b) && b))
+        {
+            _testFramework.ThrowTestException(
+                "Strict mode is enabled and no snapshot has been found " +
+                "for the current test. Create a new snapshot locally and " +
+                "rerun your tests.");
+        }
+    }
+
     private readonly struct SnapshotSegment(string? name, object? value, ISnapshotValueFormatter formatter)
         : ISnapshotSegment
     {

src/CookieCrumble/test/CookieCrumble.Tests/SnapshotTests.cs

@@ -1,12 +1,19 @@
 using System.Buffers;
+using System.Runtime.CompilerServices;
 using System.Text;
 using CookieCrumble.Formatters;
 using CookieCrumble.Xunit;
+using Xunit.Sdk;
 
 namespace CookieCrumble;
 
 public class SnapshotTests
 {
+    private const string _strictModeExceptionMessage =
+        "Strict mode is enabled and no snapshot has been found " +
+        "for the current test. Create a new snapshot locally and " +
+        "rerun your tests.";
+
     static SnapshotTests()
     {
         Snapshot.RegisterTestFramework(new XunitFramework());
@@ -109,6 +116,83 @@ public void SnapshotBuilder_Segment_Custom_Global_Serializer()
         snapshot.Match();
     }
 
+    [Theory]
+    [InlineData("on")]
+    [InlineData("true")]
+    public async Task Match_StrictMode_On(string strictMode)
+    {
+        Environment.SetEnvironmentVariable("COOKIE_CRUMBLE_STRICT_MODE", strictMode);
+
+        var snapshot = new Snapshot();
+        snapshot.Add(new MyClass { Foo = "123", });
+
+        async Task Act1() => await snapshot.MatchAsync();
+        void Act2() => snapshot.Match();
+        async Task Act3() => await snapshot.MatchMarkdownAsync();
+        void Act4() => snapshot.MatchMarkdown();
+
+        try
+        {
+            Assert.Equal(
+                _strictModeExceptionMessage,
+                (await Assert.ThrowsAsync<XunitException>(Act1)).Message);
+
+            Assert.Equal(_strictModeExceptionMessage, Assert.Throws<XunitException>(Act2).Message);
+
+            Assert.Equal(
+                _strictModeExceptionMessage,
+                (await Assert.ThrowsAsync<XunitException>(Act3)).Message);
+
+            Assert.Equal(_strictModeExceptionMessage, Assert.Throws<XunitException>(Act4).Message);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable("COOKIE_CRUMBLE_STRICT_MODE", null);
+        }
+    }
+
+    [Theory]
+    [InlineData(1, "off")]
+    [InlineData(2, "false")]
+    [InlineData(3, null)]
+    public async Task Match_StrictMode_Off(int number, string? strictMode)
+    {
+        Environment.SetEnvironmentVariable("COOKIE_CRUMBLE_STRICT_MODE", strictMode);
+
+        var snapshot = new Snapshot();
+        snapshot.Add(new MyClass { Foo = "123", });
+
+        async Task Act1() => await snapshot.SetPostFix($"MA_{number}").MatchAsync();
+        void Act2() => snapshot.SetPostFix($"M_{number}").Match();
+        async Task Act3() => await snapshot.SetPostFix($"MMA_{number}").MatchMarkdownAsync();
+        void Act4() => snapshot.SetPostFix($"MM_{number}").MatchMarkdown();
+
+        try
+        {
+            var result1 = await Record.ExceptionAsync(Act1);
+            var result2 = Record.Exception(Act2);
+            var result3 = await Record.ExceptionAsync(Act3);
+            var result4 = Record.Exception(Act4);
+
+            static string GetCallerFilePath([CallerFilePath] string filePath = "") => filePath;
+            var directory = Path.GetDirectoryName(GetCallerFilePath()) + "/__snapshots__";
+
+            File.Delete($"{directory}/SnapshotTests.Match_StrictMode_Off_MA_{number}.snap");
+            File.Delete($"{directory}/SnapshotTests.Match_StrictMode_Off_M_{number}.snap");
+            File.Delete($"{directory}/SnapshotTests.Match_StrictMode_Off_MMA_{number}.md");
+            File.Delete($"{directory}/SnapshotTests.Match_StrictMode_Off_MM_{number}.md");
+
+            Assert.Null(result1);
+            Assert.Null(result2);
+            Assert.Null(result3);
+            Assert.Null(result4);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable("COOKIE_CRUMBLE_STRICT_MODE", null);
+        }
+    }
+
     public class MyClass
     {
         public string Foo { get; set; } = "Bar";