feat(etl): implement ColumnRenameTransformer

Add transformer for renaming columns in the data stream during ETL. Supports case-insensitive column name matching and multiple renames.
2026-01-03 09:13:02 -05:00
parent f1b7809a45
commit 81cb0df6bf
2 changed files with 120 additions and 0 deletions
@@ -0,0 +1,69 @@
+using System.Data;
+using JdeScoping.DataSync.Etl.Transformers;
+using NSubstitute;
+
+namespace JdeScoping.DataSync.Tests.Etl.Transformers;
+
+public class ColumnRenameTransformerTests
+{
+    [Fact]
+    public void GetName_ReturnsRenamedColumn()
+    {
+        var source = CreateMockReader(new[] { "OldName", "Other" });
+        var transformer = new ColumnRenameTransformer(("OldName", "NewName"));
+        var reader = transformer.Transform(source);
+        Assert.Equal("NewName", reader.GetName(0));
+        Assert.Equal("Other", reader.GetName(1));
+    }
+
+    [Fact]
+    public void GetOrdinal_FindsByNewName()
+    {
+        var source = CreateMockReader(new[] { "OldName", "Other" });
+        var transformer = new ColumnRenameTransformer(("OldName", "NewName"));
+        var reader = transformer.Transform(source);
+        Assert.Equal(0, reader.GetOrdinal("NewName"));
+    }
+
+    [Fact]
+    public void GetOrdinal_OldName_ThrowsIndexOutOfRange()
+    {
+        var source = CreateMockReader(new[] { "OldName", "Other" });
+        var transformer = new ColumnRenameTransformer(("OldName", "NewName"));
+        var reader = transformer.Transform(source);
+        Assert.Throws<IndexOutOfRangeException>(() => reader.GetOrdinal("OldName"));
+    }
+
+    [Fact]
+    public void FieldCount_Unchanged()
+    {
+        var source = CreateMockReader(new[] { "OldName", "Other" });
+        var transformer = new ColumnRenameTransformer(("OldName", "NewName"));
+        var reader = transformer.Transform(source);
+        Assert.Equal(2, reader.FieldCount);
+    }
+
+    [Fact]
+    public void MultipleRenames_AllApplied()
+    {
+        var source = CreateMockReader(new[] { "A", "B", "C" });
+        var transformer = new ColumnRenameTransformer(("A", "Alpha"), ("C", "Charlie"));
+        var reader = transformer.Transform(source);
+        Assert.Equal("Alpha", reader.GetName(0));
+        Assert.Equal("B", reader.GetName(1));
+        Assert.Equal("Charlie", reader.GetName(2));
+    }
+
+    private static IDataReader CreateMockReader(string[] columns)
+    {
+        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);
+        }
+        return reader;
+    }
+}