when "dotnet test" runs test projects in parallel mode, json file writes invalid

src/coverlet.core/Coverage.cs

@@ -193,7 +193,18 @@ public CoverageResult GetCoverageResult()
 
             if (!string.IsNullOrEmpty(_mergeWith) && !string.IsNullOrWhiteSpace(_mergeWith) && File.Exists(_mergeWith))
             {
-                string json = File.ReadAllText(_mergeWith);
+                // Possible concurrency access to merge file between write/read on parallel testing
+                var json = RetryHelper.Do(() =>
+                {
+                    using (var file = File.Open(_mergeWith, FileMode.Open, FileAccess.Read, FileShare.None))
+                    {
+                        using (var reader = new StreamReader(file))
+                        {
+                            return reader.ReadToEnd();
+                        }
+                    }
+                }, () => TimeSpan.FromMilliseconds(100), 5);
+
                 coverageResult.Merge(JsonConvert.DeserializeObject<Modules>(json));
             }
 

src/coverlet.msbuild.tasks/CoverageResultTask.cs

@@ -103,7 +103,20 @@ public override bool Execute()
 
                         var report = Path.Combine(directory, filename);
                         Console.WriteLine($"  Generating report '{report}'");
-                        File.WriteAllText(report, reporter.Report(result));
+
+                        var resultContent = reporter.Report(result);
+
+                        // Possible concurrency access to merge file between write/read on parallel testing
+                        RetryHelper.Retry(() =>
+                        {
+                            using (var file = File.Open(report, FileMode.Create, FileAccess.Write, FileShare.None))
+                            {
+                                using (var writer = new StreamWriter(file))
+                                {
+                                    writer.Write(resultContent);
+                                }
+                            }
+                        }, () => TimeSpan.FromMilliseconds(100), 5);
                     }
                 }