feat(etl): implement ColumnDropTransformer

Add a data transformer that removes specified columns from the data stream. Columns are matched by name (case-insensitive) and multiple columns can be dropped in a single transformer. Includes comprehensive tests using NSubstitute for mock IDataReader.
2026-01-03 09:10:54 -05:00
parent 6e7bcadf68
commit f1b7809a45
2 changed files with 153 additions and 0 deletions
@@ -0,0 +1,87 @@
+using System.Data;
+using JdeScoping.DataSync.Etl.Transformers;
+using NSubstitute;
+
+namespace JdeScoping.DataSync.Tests.Etl.Transformers;
+
+public class ColumnDropTransformerTests
+{
+    [Fact]
+    public void FieldCount_ExcludesDroppedColumns()
+    {
+        var source = CreateMockReader(new[] { "Id", "Name", "DropMe", "Value" });
+        var transformer = new ColumnDropTransformer("DropMe");
+        var reader = transformer.Transform(source);
+        Assert.Equal(3, reader.FieldCount);
+    }
+
+    [Fact]
+    public void GetName_SkipsDroppedColumns()
+    {
+        var source = CreateMockReader(new[] { "Id", "Name", "DropMe", "Value" });
+        var transformer = new ColumnDropTransformer("DropMe");
+        var reader = transformer.Transform(source);
+        Assert.Equal("Id", reader.GetName(0));
+        Assert.Equal("Name", reader.GetName(1));
+        Assert.Equal("Value", reader.GetName(2));
+    }
+
+    [Fact]
+    public void GetOrdinal_ReturnsRemappedOrdinal()
+    {
+        var source = CreateMockReader(new[] { "Id", "Name", "DropMe", "Value" });
+        var transformer = new ColumnDropTransformer("DropMe");
+        var reader = transformer.Transform(source);
+        Assert.Equal(0, reader.GetOrdinal("Id"));
+        Assert.Equal(1, reader.GetOrdinal("Name"));
+        Assert.Equal(2, reader.GetOrdinal("Value"));
+    }
+
+    [Fact]
+    public void GetOrdinal_DroppedColumn_ThrowsIndexOutOfRange()
+    {
+        var source = CreateMockReader(new[] { "Id", "Name", "DropMe", "Value" });
+        var transformer = new ColumnDropTransformer("DropMe");
+        var reader = transformer.Transform(source);
+        Assert.Throws<IndexOutOfRangeException>(() => reader.GetOrdinal("DropMe"));
+    }
+
+    [Fact]
+    public void GetValue_ReturnsCorrectValues()
+    {
+        var source = CreateMockReader(new[] { "Id", "Name", "DropMe", "Value" }, new object[] { 1, "Test", "Dropped", 42 });
+        source.Read().Returns(true);
+        var transformer = new ColumnDropTransformer("DropMe");
+        var reader = transformer.Transform(source);
+        reader.Read();
+        Assert.Equal(1, reader.GetValue(0));
+        Assert.Equal("Test", reader.GetValue(1));
+        Assert.Equal(42, reader.GetValue(2));
+    }
+
+    [Fact]
+    public void MultipleDroppedColumns_AllExcluded()
+    {
+        var source = CreateMockReader(new[] { "Id", "Drop1", "Name", "Drop2", "Value" });
+        var transformer = new ColumnDropTransformer("Drop1", "Drop2");
+        var reader = transformer.Transform(source);
+        Assert.Equal(3, reader.FieldCount);
+        Assert.Equal("Id", reader.GetName(0));
+        Assert.Equal("Name", reader.GetName(1));
+        Assert.Equal("Value", reader.GetName(2));
+    }
+
+    private static IDataReader CreateMockReader(string[] columns, object[]? values = null)
+    {
+        var reader = Substitute.For<IDataReader>();
+        reader.FieldCount.Returns(columns.Length);
+        for (int i = 0; i < columns.Length; i++)
+        {
+            var index = i;
+            reader.GetName(index).Returns(columns[index]);
+            reader.GetOrdinal(columns[index]).Returns(index);
+            if (values != null) reader.GetValue(index).Returns(values[index]);
+        }
+        return reader;
+    }
+}