Make validation data param mandatory; remove GetFirstPipeline sample (dotnet#10)

* Make validation data param mandatory; remove GetFirstPipeline sample

* remove deprecated todo

Author: daholste

src/AutoML/API/MLContextAutoFitExtensions.cs

@@ -11,7 +11,7 @@ public static class RegressionExtensions
         public static RegressionResult AutoFit(this RegressionContext context,
             IDataView trainData,
             string label,
-            IDataView validationData = null,
+            IDataView validationData,
             AutoFitSettings settings = null,
             IEnumerable<(string, ColumnPurpose)> purposeOverrides = null,
             CancellationToken cancellationToken = default,
@@ -20,12 +20,11 @@ public static RegressionResult AutoFit(this RegressionContext context,
             return AutoFit(context, trainData, label, validationData, settings,
                 purposeOverrides, cancellationToken, iterationCallback, null);
         }
-
-        // todo: instead of internal methods, use static debug class w/ singleton logger?
+        
         internal static RegressionResult AutoFit(this RegressionContext context,
             IDataView trainData,
             string label,
-            IDataView validationData = null,
+            IDataView validationData,
             AutoFitSettings settings = null,
             IEnumerable<(string, ColumnPurpose)> purposeOverrides = null,
             CancellationToken cancellationToken = default,
@@ -60,7 +59,7 @@ public static class BinaryClassificationExtensions
         public static BinaryClassificationResult AutoFit(this BinaryClassificationContext context,
             IDataView trainData,
             string label,
-            IDataView validationData = null,
+            IDataView validationData,
             AutoFitSettings settings = null,
             IEnumerable<(string, ColumnPurpose)> purposeOverrides = null,
             CancellationToken cancellationToken = default,
@@ -73,7 +72,7 @@ public static BinaryClassificationResult AutoFit(this BinaryClassificationContex
         internal static BinaryClassificationResult AutoFit(this BinaryClassificationContext context,
             IDataView trainData,
             string label,
-            IDataView validationData = null,
+            IDataView validationData,
             AutoFitSettings settings = null,
             IEnumerable<(string, ColumnPurpose)> purposeOverrides = null,
             CancellationToken cancellationToken = default,
@@ -109,7 +108,7 @@ public static class MulticlassExtensions
         public static MulticlassClassificationResult AutoFit(this MulticlassClassificationContext context,
             IDataView trainData,
             string label,
-            IDataView validationData = null,
+            IDataView validationData,
             AutoFitSettings settings = null,
             IEnumerable<(string, ColumnPurpose)> purposeOverrides = null,
             CancellationToken cancellationToken = default,
@@ -122,7 +121,7 @@ public static MulticlassClassificationResult AutoFit(this MulticlassClassificati
         internal static MulticlassClassificationResult AutoFit(this MulticlassClassificationContext context,
             IDataView trainData,
             string label,
-            IDataView validationData = null,
+            IDataView validationData,
             AutoFitSettings settings = null,
             IEnumerable<(string, ColumnPurpose)> purposeOverrides = null,
             CancellationToken cancellationToken = default,

src/AutoML/Utils/UserInputValidationUtil.cs

@@ -86,7 +86,7 @@ private static void ValidateLabel(IDataView trainData, IDataView validationData,
                 throw new ArgumentException(nameof(label), $"Provided label column '{label}' not found in training data.");
             }
 
-            if (validationData != null && validationData.Schema.GetColumnOrNull(label) == null)
+            if (validationData.Schema.GetColumnOrNull(label) == null)
             {
                 throw new ArgumentException(nameof(label), $"Provided label column '{label}' not found in validation data.");
             }
@@ -124,7 +124,7 @@ private static void ValidateValidationData(IDataView trainData, IDataView valida
         {
             if(validationData == null)
             {
-                return;
+                throw new ArgumentNullException(nameof(validationData), "Validation data cannot be null");
             }
 
             const string schemaMismatchError = "Training data and validation data schemas do not match.";
@@ -187,7 +187,7 @@ private static void ValidatePurposeOverrides(IDataView trainData, IDataView vali
                     throw new ArgumentException(nameof(purposeOverride), $"Purpose override column name '{colName}' not found in training data.");
                 }
 
-                if(validationData != null && validationData.Schema.GetColumnOrNull(colName) == null)
+                if(validationData.Schema.GetColumnOrNull(colName) == null)
                 {
                     throw new ArgumentException(nameof(purposeOverride), $"Purpose override column name '{colName}' not found in validation data.");
                 }