Passing test sources parameter to data collectors

RFCs/0026-DataCollector-Extensibility-Sources-Parameter.md

@@ -0,0 +1,74 @@
+# 0026 DataCollector Extensibility - Adding testSources parameter
+
+## Summary
+Exposing `testSources` parameter to datacollector extensions. List of test sources can be used by datacollectors for processing before test run start.
+
+## Motivation
+Data collector might need test sources list while initialization. Example: Static code coverage data collector needs to instrument the test sources before test run start.
+
+## Using testSources parameter in DataCollector
+
+Refer [datacollector](https://github.com/Microsoft/vstest/tree/master/test/TestAssets/OutOfProcDataCollector) doc for more details on how to write a datacollector.
+To use `testSources` parameter in `DataCollector`:
+
+```csharp
+using Microsoft.VisualStudio.TestPlatform.ObjectModel.DataCollection;
+
+[DataCollectorFriendlyName("NewDataCollector")]
+[DataCollectorTypeUri("my://new/datacollector")]
+public class NewDataCollector : DataCollector
+{
+    private string logFileName;
+	private IEnumerable<string> testSources;
+    private DataCollectionEnvironmentContext context;
+
+    public override void Initialize(
+            System.Xml.XmlElement configurationElement,
+            DataCollectionEvents events,
+            DataCollectionSink dataSink,
+            DataCollectionLogger logger,
+            DataCollectionEnvironmentContext environmentContext)
+    {
+        events.SessionStart += this.SessionStarted_Handler;
+        events.TestCaseStart += this.Events_TestCaseStart;
+        this.logFileName = configurationElement["LogFileName"];
+		this.context = environmentContext;
+    }
+
+	public override void Initialize(
+            System.Xml.XmlElement configurationElement,
+			IEnumerable<string> testSources,
+            DataCollectionEvents events,
+            DataCollectionSink dataSink,
+            DataCollectionLogger logger,
+            DataCollectionEnvironmentContext environmentContext)
+    {
+		this.testSources = testSources;
+		base.Initialize(configurationElement, events, dataSink, logger, environmentContext);
+    }
+
+    private void SessionStarted_Handler(object sender, SessionStartEventArgs args)
+    {
+        var filename = Path.Combine(AppContext.BaseDirectory, logFileName);
+        File.WriteAllText(filename, "SessionStarted");
+        this.dataCollectionSink.SendFileAsync(this.context.SessionDataCollectionContext, filename, true);
+        this.logger.LogWarning(this.context.SessionDataCollectionContext, "SessionStarted");
+    }
+
+
+    private void Events_TestCaseStart(object sender, TestCaseStartEventArgs e)
+    {
+        this.logger.LogWarning(this.context.SessionDataCollectionContext, "TestCaseStarted " + e.TestCaseName);
+    }
+}
+```
+DataCollector exposes
+
+`Initialize(System.Xml.XmlElement configurationElement, IEnumerable<string> testSources, DataCollectionEvents events, DataCollectionSink dataSink, DataCollectionLogger logger, DataCollectionEnvironmentContext environmentContext)`
+
+in addition to existing
+
+`Initialize(System.Xml.XmlElement configurationElement, DataCollectionEvents events, DataCollectionSink dataSink, DataCollectionLogger logger, DataCollectionEnvironmentContext environmentContext)`
+
+to expose `testSources` list to `DataCollector`.
+`testSources` parameter is an IEnumerable of test source file path.

docs/extensions/datacollector.md

@@ -37,7 +37,8 @@ public class NewDataCollector : DataCollector
     {
         events.SessionStart += this.SessionStarted_Handler;
         events.TestCaseStart += this.Events_TestCaseStart;
-        logFileName = configurationElement["LogFileName"];
+        this.logFileName = configurationElement["LogFileName"];
+        this.context = environmentContext;
     }
 
     private void SessionStarted_Handler(object sender, SessionStartEventArgs args)