lock AssignTargetAssembly

Author: SimonCropp

src/Directory.Build.props

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project>
   <PropertyGroup>
-    <Version>29.0.0-beta.1</Version>
+    <Version>29.0.0-beta.2</Version>
     <NoWarn>CA1822;CS1591;CS0649;xUnit1026;xUnit1013;CS1573;VerifyTestsProjectDir;VerifySetParameters;PolyFillTargetsForNuget;xUnit1051</NoWarn>
     <ImplicitUsings>enable</ImplicitUsings>
     <LangVersion>preview</LangVersion>

src/Verify/VerifierSettings_TargetAssembly.cs

@@ -25,25 +25,35 @@ public static Assembly Assembly
         }
     }
 
+    static Lock locker = new();
+
     public static void AssignTargetAssembly(Assembly assembly)
     {
         if (VerifierSettings.assembly is not null)
         {
             return;
         }
 
-        VerifierSettings.assembly = assembly;
-        Namer.UseAssembly(assembly);
-        IoHelpers.MapPathsForCallingAssembly(assembly);
-        ProjectDir = AttributeReader.GetProjectDirectory(assembly);
-        AttributeReader.TryGetSolutionDirectory(assembly, out var solutionDir);
-        SolutionDir = solutionDir;
-        if (AttributeReader.TryGetTargetFrameworks(assembly, out var targetFrameworks))
+        lock (locker)
         {
-            TargetsMultipleFramework = targetFrameworks.Contains(';');
-        }
+            if (VerifierSettings.assembly is not null)
+            {
+                return;
+            }
 
-        SolutionDir = solutionDir;
-        ApplyScrubbers.UseAssembly(solutionDir, ProjectDir);
+            VerifierSettings.assembly = assembly;
+            Namer.UseAssembly(assembly);
+            IoHelpers.MapPathsForCallingAssembly(assembly);
+            ProjectDir = AttributeReader.GetProjectDirectory(assembly);
+            AttributeReader.TryGetSolutionDirectory(assembly, out var solutionDir);
+            SolutionDir = solutionDir;
+            if (AttributeReader.TryGetTargetFrameworks(assembly, out var targetFrameworks))
+            {
+                TargetsMultipleFramework = targetFrameworks.Contains(';');
+            }
+
+            SolutionDir = solutionDir;
+            ApplyScrubbers.UseAssembly(solutionDir, ProjectDir);
+        }
     }
 }