changes after feedback

Author: GOEddieUK

src/csharp/Microsoft.Spark.E2ETest/IpcTests/ML/Feature/BucketizerTests.cs

@@ -28,10 +28,10 @@ public void TestBucketizer()
             var expectedSplits =
                 new double[] { double.MinValue, 0.0, 10.0, 50.0, double.MaxValue };
 
-            string expectedHandle = "skip";
-            string expectedUid = "uid";
-            string expectedInputCol = "input_col";
-            string expectedOutputCol = "output_col";
+            const string expectedHandle = "skip";
+            const string expectedUid = "uid";
+            const string expectedInputCol = "input_col";
+            const string expectedOutputCol = "output_col";
 
             var bucketizer = new Bucketizer(expectedUid);
             bucketizer.SetInputCol(expectedInputCol)

src/csharp/Microsoft.Spark.E2ETest/IpcTests/ML/Feature/FeatureBaseTests.cs

@@ -10,6 +10,12 @@ namespace Microsoft.Spark.E2ETest.IpcTests.ML.Feature
 {
     public static class FeatureBaseTests<T>
     {
+        /// <summary>
+        /// Tests the common functionality across all ML.Feature classes.
+        /// </summary>
+        /// <param name="testObject">The object that implemented FeatureBase</param>
+        /// <param name="paramName">The name of a parameter that can be set on this object</param>
+        /// <param name="paramValue">A parameter value that can be set on this object</param>
         internal static void TestBase(
             FeatureBase<T> testObject, 
             string paramName, 

src/csharp/Microsoft.Spark.E2ETest/IpcTests/ML/Feature/FeatureHasherTests.cs

@@ -20,7 +20,11 @@ public FeatureHasherTests(SparkFixture fixture)
         {
             _spark = fixture.Spark;
         }
-
+        
+        /// <summary>
+        /// Create a <see cref="DataFrame"/>, create a <see cref="FeatureHasher"/> and test the
+        /// available methods. Test the FeatureBase methods using <see cref="FeatureBaseTests"/>.
+        /// </summary>
         [Fact]
         public void TestFeatureHasher()
         {

src/csharp/Microsoft.Spark/ML/Feature/FeatureHasher.cs

@@ -61,7 +61,7 @@ public FeatureHasher SetCategoricalCols(IEnumerable<string> value) =>
         /// Gets the columns that the <see cref="FeatureHasher"/> should read from and convert into
         /// hashes. This would have been set by SetInputCol.
         /// </summary>
-        /// <returns>IEnumerable&lt;string&gt;, the input columns</returns>
+        /// <returns>List of the input columns, set by SetInputCols</returns>
         public IEnumerable<string> GetInputCols() => (string[])_jvmObject.Invoke("getInputCols");
 
         /// <summary>
@@ -88,7 +88,7 @@ public FeatureHasher SetInputCols(IEnumerable<string> value) =>
         /// the numFeatures parameter; otherwise the features will not be mapped evenly to the
         /// columns.
         /// </summary>
-        /// <param name="value">int</param>
+        /// <param name="value">int value of number of features</param>
         /// <returns>New <see cref="FeatureHasher"/> object</returns>
         public FeatureHasher SetNumFeatures(int value) => 
             WrapAsFeatureHasher(_jvmObject.Invoke("setNumFeatures", value));
@@ -101,8 +101,7 @@ public FeatureHasher SetNumFeatures(int value) =>
         public string GetOutputCol() => (string)_jvmObject.Invoke("getOutputCol");
 
         /// <summary>
-        /// The <see cref="FeatureHasher"/> will create a new column in the DataFrame, this is the
-        /// name of the new column.
+        /// Sets the name of the new column in the <see cref="DataFrame"/> created by Transform.
         /// </summary>
         /// <param name="value">The name of the new column which will contain the hash</param>
         /// <returns>New <see cref="FeatureHasher"/> object</returns>
@@ -122,7 +121,7 @@ public DataFrame Transform(DataFrame value) =>
         /// Check transform validity and derive the output schema from the input schema.
         /// 
         /// This checks for validity of interactions between parameters during Transform and
-        /// raises an exception if any parameter value is invalid.   
+        /// raises an exception if any parameter value is invalid.
         ///
         /// Typical implementation should first conduct verification on schema change and parameter
         /// validity, including complex parameter interaction checks.