add basic autofit regression test (dotnet#28)

Author: daholste

src/Test/AutoFitTests.cs

@@ -52,5 +52,29 @@ public void AutoFitMultiTest()
             Assert.IsNotNull(best?.BestPipeline?.Model);
             Assert.IsTrue(best.BestPipeline.Metrics.AccuracyMicro > 0.80);
         }
+
+        [TestMethod]
+        public void AutoFitRegressionTest()
+        {
+            var context = new MLContext();
+            var dataPath = DatasetUtil.DownloadMlNetGeneratedRegressionDataset();
+            var columnInference = context.Data.InferColumns(dataPath, DatasetUtil.MlNetGeneratedRegressionLabel, true);
+            var textLoader = context.Data.CreateTextReader(columnInference);
+            var trainData = textLoader.Read(dataPath);
+            var validationData = trainData.Take(20);
+            trainData = trainData.Skip(20);
+            var best = context.Regression.AutoFit(trainData, DatasetUtil.MlNetGeneratedRegressionLabel, validationData, settings:
+                new AutoFitSettings()
+                {
+                    StoppingCriteria = new ExperimentStoppingCriteria()
+                    {
+                        MaxIterations = 1,
+                        TimeOutInMinutes = 1000000000
+                    }
+                }, debugLogger: null);
+
+            Assert.IsNotNull(best?.BestPipeline?.Model);
+            Assert.IsTrue(best.BestPipeline.Metrics.RSquared > 0.9);
+        }
     }
 }

src/Test/DatasetUtil.cs

@@ -9,6 +9,7 @@ internal static class DatasetUtil
     {
         public const string UciAdultLabel = DefaultColumnNames.Label;
         public const string TrivialDatasetLabel = DefaultColumnNames.Label;
+        public const string MlNetGeneratedRegressionLabel = "target";
 
         private static IDataView _uciAdultDataView;
 
@@ -29,6 +30,9 @@ public static string DownloadUciAdultDataset() =>
         public static string DownloadTrivialDataset() =>
             DownloadIfNotExists("https://raw.githubusercontent.com/dotnet/machinelearning/eae76959e6714af44caa212e102a5f06f0110e72/test/data/trivial-train.tsv", "trivial.dataset");
 
+        public static string DownloadMlNetGeneratedRegressionDataset() =>
+            DownloadIfNotExists("https://raw.githubusercontent.com/dotnet/machinelearning/e78971ea6fd736038b4c355b840e5cbabae8cb55/test/data/generated_regression_dataset.csv", "mlnet_generated_regression.dataset");
+
         private static string DownloadIfNotExists(string baseGitPath, string dataFile)
         {
             // if file doesn't already exist, download it