Fix failure to process coverage reports for parallel builds

src/coverlet.console/Program.cs

@@ -50,7 +50,7 @@ static int Main(string[] args)
                 if (!target.HasValue())
                     throw new CommandParsingException(app, "Target must be specified.");
 
-                Coverage coverage = new Coverage(module.Value, includeFilters.Values.ToArray(), includeDirectories.Values.ToArray(), excludeFilters.Values.ToArray(), excludedSourceFiles.Values.ToArray(), excludeAttributes.Values.ToArray(), singleHit.HasValue(), mergeWith.Value(), useSourceLink.HasValue(), logger);
+                Coverage coverage = new Coverage(module.Value, includeFilters.Values.ToArray(), includeDirectories.Values.ToArray(), excludeFilters.Values.ToArray(), excludedSourceFiles.Values.ToArray(), excludeAttributes.Values.ToArray(), singleHit.HasValue(), mergeWith.Value(), useSourceLink.HasValue(), logger, Guid.NewGuid().ToString());
                 coverage.PrepareModules();
 
                 Process process = new Process();

src/coverlet.core/Coverage.cs

@@ -41,7 +41,8 @@ public Coverage(string module,
             bool singleHit,
             string mergeWith,
             bool useSourceLink,
-            ILogger logger)
+            ILogger logger,
+            string identifier)
         {
             _module = module;
             _includeFilters = includeFilters;
@@ -53,8 +54,8 @@ public Coverage(string module,
             _mergeWith = mergeWith;
             _useSourceLink = useSourceLink;
             _logger = logger;
+            _identifier = identifier;
 
-            _identifier = Guid.NewGuid().ToString();
             _results = new List<InstrumenterResult>();
         }
 

src/coverlet.msbuild.tasks/CoverageResultTask.cs

@@ -13,13 +13,21 @@ namespace Coverlet.MSbuild.Tasks
 {
     public class CoverageResultTask : Task
     {
+        private string _identifier;
         private string _output;
         private string _format;
         private double _threshold;
         private string _thresholdType;
         private string _thresholdStat;
         private MSBuildLogger _logger;
 
+        [Required]
+        public string Identifier
+        {
+            get { return _identifier; }
+            set { _identifier = value; }
+        }
+
         [Required]
         public string Output
         {
@@ -66,7 +74,7 @@ public override bool Execute()
             {
                 Console.WriteLine("\nCalculating coverage result...");
 
-                var coverage = InstrumentationTask.Coverage;
+                var coverage = InstrumentationTask.Coverage[Identifier];
                 var result = coverage.GetCoverageResult();
 
                 var directory = Path.GetDirectoryName(_output);

src/coverlet.msbuild.tasks/InstrumentationTask.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Immutable;
 using Coverlet.Core;
 using Microsoft.Build.Framework;
 using Microsoft.Build.Utilities;
@@ -7,7 +8,7 @@ namespace Coverlet.MSbuild.Tasks
 {
     public class InstrumentationTask : Task
     {
-        private static Coverage _coverage;
+        private static ImmutableDictionary<string, Coverage> _coverage;
         private string _path;
         private string _include;
         private string _includeDirectory;
@@ -19,7 +20,7 @@ public class InstrumentationTask : Task
         private bool _useSourceLink;
         private readonly MSBuildLogger _logger;
 
-        internal static Coverage Coverage
+        internal static ImmutableDictionary<string, Coverage> Coverage
         {
             get { return _coverage; }
         }
@@ -31,6 +32,13 @@ public string Path
             set { _path = value; }
         }
 
+        [Required]
+        public string Identifier
+        {
+            get;
+            set;
+        }
+
         public string Include
         {
             get { return _include; }
@@ -94,8 +102,10 @@ public override bool Execute()
                 var excludedSourceFiles = _excludeByFile?.Split(',');
                 var excludeAttributes = _excludeByAttribute?.Split(',');
 
-                _coverage = new Coverage(_path, includeFilters, includeDirectories, excludeFilters, excludedSourceFiles, excludeAttributes, _singleHit, _mergeWith, _useSourceLink, _logger);
-                _coverage.PrepareModules();
+                var coverage = new Coverage(_path, includeFilters, includeDirectories, excludeFilters, excludedSourceFiles, excludeAttributes, _singleHit, _mergeWith, _useSourceLink, _logger, Identifier);
+                coverage.PrepareModules();
+
+                ImmutableInterlocked.AddOrUpdate(ref _coverage, Identifier, coverage, (_1, _2) => coverage);
             }
             catch (Exception ex)
             {

src/coverlet.msbuild.tasks/coverlet.msbuild.props

@@ -1,6 +1,7 @@
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <CollectCoverage Condition="$(CollectCoverage) == ''">false</CollectCoverage>
+    <CoverletIdentifier>$([System.Guid]::NewGuid())</CoverletIdentifier>
     <Include Condition="$(Include) == ''"></Include>
     <IncludeDirectory Condition="$(IncludeDirectory) == ''"></IncludeDirectory>
     <Exclude Condition="$(Exclude) == ''"></Exclude>

src/coverlet.msbuild.tasks/coverlet.msbuild.targets

@@ -7,6 +7,7 @@
     <Coverlet.MSbuild.Tasks.InstrumentationTask
       Condition="'$(VSTestNoBuild)' == 'true' and $(CollectCoverage) == 'true'"
       Path="$(TargetPath)"
+      Identifier="$(CoverletIdentifier)"
       Include="$(Include)"
       IncludeDirectory="$(IncludeDirectory)"
       Exclude="$(Exclude)"
@@ -21,6 +22,7 @@
     <Coverlet.MSbuild.Tasks.InstrumentationTask
       Condition="'$(VSTestNoBuild)' != 'true' and $(CollectCoverage) == 'true'"
       Path="$(TargetPath)"
+      Identifier="$(CoverletIdentifier)"
       Include="$(Include)"
       IncludeDirectory="$(IncludeDirectory)"
       Exclude="$(Exclude)"
@@ -34,6 +36,7 @@
   <Target Name="GenerateCoverageResult" AfterTargets="VSTest">
     <Coverlet.MSbuild.Tasks.CoverageResultTask
       Condition="$(CollectCoverage) == 'true'"
+      Identifier="$(CoverletIdentifier)"
       Output="$(CoverletOutput)"
       OutputFormat="$(CoverletOutputFormat)"
       Threshold="$(Threshold)"

test/coverlet.core.tests/CoverageTests.cs

@@ -22,7 +22,7 @@ public void TestCoverage()
 
             // TODO: Find a way to mimick hits
 
-            var coverage = new Coverage(Path.Combine(directory.FullName, Path.GetFileName(module)), Array.Empty<string>(), Array.Empty<string>(), Array.Empty<string>(), Array.Empty<string>(), Array.Empty<string>(), false, string.Empty, false, new Mock<ILogger>().Object);
+            var coverage = new Coverage(Path.Combine(directory.FullName, Path.GetFileName(module)), Array.Empty<string>(), Array.Empty<string>(), Array.Empty<string>(), Array.Empty<string>(), Array.Empty<string>(), false, string.Empty, false, new Mock<ILogger>().Object, Guid.NewGuid().ToString());
             coverage.PrepareModules();
 
             var result = coverage.GetCoverageResult();