Fix Go CLI cyclic dependency graph (#103)

* Fix Go CLI cyclic dependency graph

Author: grvillic

Diff for: src/Microsoft.ComponentDetection.Detectors/go/GoComponentDetector.cs

@@ -33,15 +33,15 @@ public class GoComponentDetector : FileComponentDetector
 
         public override IEnumerable<ComponentType> SupportedComponentTypes { get; } = new[] { ComponentType.Go };
 
-        public override int Version => 3;
+        public override int Version => 4;
 
         private HashSet<string> projectRoots = new HashSet<string>();
 
         protected override async Task OnFileFound(ProcessRequest processRequest, IDictionary<string, string> detectorArgs)
         {
             var singleFileComponentRecorder = processRequest.SingleFileComponentRecorder;
             var file = processRequest.ComponentStream;
-            
+
             var projectRootDirectory = Directory.GetParent(file.Location);
             if (projectRoots.Any(path => projectRootDirectory.FullName.StartsWith(path)))
             {
@@ -57,9 +57,10 @@ protected override async Task OnFileFound(ProcessRequest processRequest, IDictio
                     wasGoCliScanSuccessful = await UseGoCliToScan(file.Location, singleFileComponentRecorder);
                 }
             }
-            catch
+            catch (Exception ex)
             {
-                Logger.LogInfo("Failed to detect components using go cli.");
+                Logger.LogError($"Failed to detect components using go cli. Location: {file.Location}");
+                Logger.LogException(ex, isError: true, printException: true);
             }
             finally
             {
@@ -231,7 +232,12 @@ private void PopulateDependencyGraph(string goGraphOutput, ISingleFileComponentR
                 }
                 else if (isParentParsed && isChildParsed)
                 {
-                    // Go output guarantees that all parents will be output before children
+                    // Go can have a cyclic dependency between modules, which could cause child components to be listed first than parents. Reproducible with Go 1.16
+                    if (singleFileComponentRecorder.GetComponent(parentComponent.Id) == null)
+                    {
+                        singleFileComponentRecorder.RegisterUsage(new DetectedComponent(parentComponent));
+                    }
+
                     singleFileComponentRecorder.RegisterUsage(new DetectedComponent(childComponent), parentComponentId: parentComponent.Id);
                 }
                 else

Diff for: test/Microsoft.ComponentDetection.Detectors.Tests/GoComponentDetectorTests.cs

@@ -335,6 +335,34 @@ public async Task TestGoDetector_GoGraphHappyPath()
             Assert.AreEqual(4, detectedComponents.Count());
         }
 
+        [TestMethod]
+        public async Task TestGoDetector_GoGraphCyclicDependencies()
+        {
+            var goGraph = @"
+github.com/prometheus/[email protected] github.com/prometheus/[email protected]
+github.com/prometheus/[email protected] github.com/prometheus/[email protected]";
+            commandLineMock.Setup(x => x.CanCommandBeLocated("go", null, It.IsAny<DirectoryInfo>(), It.IsAny<string[]>()))
+                .ReturnsAsync(true);
+
+            commandLineMock.Setup(x => x.ExecuteCommand("go", null, It.IsAny<DirectoryInfo>(), new[] { "mod", "graph" }))
+                .ReturnsAsync(new CommandLineExecutionResult
+                {
+                    ExitCode = 0,
+                    StdOut = goGraph,
+                });
+
+            envVarService.Setup(x => x.DoesEnvironmentVariableExist("EnableGoCliScan")).Returns(true);
+
+            var (scanResult, componentRecorder) = await detectorTestUtility
+                                                    .WithFile("go.mod", string.Empty)
+                                                    .ExecuteDetector();
+
+            Assert.AreEqual(ProcessingResultCode.Success, scanResult.ResultCode);
+
+            var detectedComponents = componentRecorder.GetDetectedComponents();
+            Assert.AreEqual(3, detectedComponents.Count());
+        }
+
         [TestMethod]
         public async Task TestGoDetector_GoCliRequiresEnvVarToRun()
         {