feat: public interface IReadOnlyDataRow to handle wrappers around Dat…

…aRow (#252)

Expressif.Testing/ContextTest.cs

@@ -1,5 +1,6 @@
 using Expressif.Values;
 using Expressif.Values.Special;
+using NUnit.Framework.Constraints;
 using System.Data;
 
 namespace Expressif.Testing;
@@ -220,7 +221,7 @@ public void CurrentObjectName_DictionaryWithUnavailableKey_ThrowsException()
     }
 
     [Test]
-    public void CurrentObjectName_ObjectWithUnavailableProperty_ThrowsException()
+    public void CurrentObjectName_AnonymousObjectWithUnavailableProperty_ThrowsException()
     {
         var context = new Context();
         context.CurrentObject.Set(new { foo = 123 });
@@ -232,7 +233,38 @@ public void CurrentObjectName_ObjectWithUnavailableProperty_ThrowsException()
         Assert.Multiple(() =>
         {
             Assert.That(() => context.CurrentObject["foo"], Throws.Nothing);
-            Assert.That(() => context.CurrentObject["bar"], Throws.TypeOf<ArgumentOutOfRangeException>());
+            Assert.That(() => context.CurrentObject["bar"], Throws.TypeOf<ArgumentException>()
+                .With.Message.EqualTo("Cannot find a property named 'bar' in the object of type '<>f__AnonymousType1`1'."));
+        });
+    }
+
+    private record ObjectTest(string Name) { }
+    [Test]
+    public void CurrentObjectName_ObjectWithUnavailableProperty_ThrowsException()
+    {
+        var context = new Context();
+        context.CurrentObject.Set(new ObjectTest("foo"));
+        Assert.That(context.CurrentObject.Contains("Bar"), Is.False);
+        Assert.Multiple(() =>
+        {
+            Assert.That(() => context.CurrentObject["Bar"], Throws.TypeOf<ArgumentException>()
+                .With.Message.EqualTo("Cannot find a property named 'Bar' in the object of type 'ObjectTest'."));
+        });
+    }
+
+    [Test]
+    public void CurrentObjectName_ObjectNull_ThrowsException()
+    {
+        var context = new Context();
+        context.CurrentObject.Set(null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(context.CurrentObject.Contains("bar"), Is.False);
+        });
+        Assert.Multiple(() =>
+        {
+            Assert.That(() => context.CurrentObject["bar"], Throws.TypeOf<ArgumentException>()
+                .With.Message.EqualTo("Cannot find a property named 'bar' in the object of type 'null'."));
         });
     }
 
@@ -416,4 +448,66 @@ public void CurrentObjectValue_Any_CorrectResult()
         context.CurrentObject.Set(new List<int>() { 123, 456 });
         Assert.That(context.CurrentObject.Value, Is.AssignableTo<IList<int>>());
     }
+
+    private class DataRowWrapper(DataRow row) : IReadOnlyDataRow
+    {
+        private DataRow Row { get; } = row;
+
+        public object? this[string columnName] => Row[columnName];
+
+        public object? this[int index] => Row[index];
+
+        public int ColumnsCount => Row.Table.Columns.Count;
+
+        public bool ContainsColumn(string columnName) => Row.Table.Columns.Contains(columnName);
+    }
+
+    [Test]
+    public void CurrentObjectIndex_IReadOnlyDataRowWithUnavailableColumn_ThrowsException()
+    {
+        var dt = new DataTable();
+        dt.Columns.Add("foo", typeof(int));
+        var row = dt.NewRow();
+        row.ItemArray = new object[] { 123 };
+        dt.Rows.Add(row);
+        var wrapper = new DataRowWrapper(row);
+
+        var context = new Context();
+        context.CurrentObject.Set(wrapper);
+        Assert.Multiple(() =>
+        {
+            Assert.That(context.CurrentObject.Contains(0), Is.True);
+            Assert.That(context.CurrentObject.Contains(1), Is.False);
+        });
+        Assert.Multiple(() =>
+        {
+            Assert.That(() => context.CurrentObject[0], Throws.Nothing);
+            Assert.That(() => context.CurrentObject[1], Throws.TypeOf<ArgumentOutOfRangeException>());
+        });
+    }
+
+    [Test]
+    public void CurrentObjectName_IReadOnlyDataRowWithExistingColumn_ValueReturned()
+    {
+        var dt = new DataTable();
+        dt.Columns.Add("foo", typeof(int));
+        dt.Columns.Add("bar", typeof(object));
+        var row = dt.NewRow();
+        row.ItemArray = new object[] { 123, 456 };
+        dt.Rows.Add(row);
+        var wrapper = new DataRowWrapper(row);
+
+        var context = new Context();
+        context.CurrentObject.Set(wrapper);
+        Assert.Multiple(() =>
+        {
+            Assert.That(context.CurrentObject.Contains("foo"), Is.True);
+            Assert.That(context.CurrentObject.Contains("bar"), Is.True);
+        });
+        Assert.Multiple(() =>
+        {
+            Assert.That(context.CurrentObject["foo"], Is.EqualTo(123));
+            Assert.That(context.CurrentObject["bar"], Is.EqualTo(456));
+        });
+    }
 }

Expressif/Values/ContextObject.cs

@@ -14,9 +14,9 @@ public class ContextObject
     public object? Value { get; private set; }
     private PropertyInfo[]? Cache { get; set; }
 
-    public void Set(object value)
+    public void Set(object? value)
     {
-        if (Value == null || Value.GetType() != value.GetType())
+        if (value == null || Value == null || Value.GetType() != value.GetType())
             Cache = null;
         Value = value;
     }
@@ -25,6 +25,7 @@ public bool Contains(string name)
         => Value switch
         {
             DataRow row => row.Table.Columns.Contains(name),
+            IReadOnlyDataRow row => row.ContainsColumn(name),
             IDictionary dico => dico.Contains(name),
             IList => throw new NotNameableContextObjectException(Value),
             _ => TryRetrieveObjectProperty(name, out var _),
@@ -37,15 +38,16 @@ public object? this[string name]
             return Value switch
             {
                 DataRow row => row.Table.Columns.Contains(name) ? row[name] : throw new ArgumentOutOfRangeException(name),
-                IDictionary dico =>  dico.Contains(name) ? dico[name] : throw new ArgumentOutOfRangeException(name),
+                IReadOnlyDataRow row => row.ContainsColumn(name) ? row[name] : throw new ArgumentOutOfRangeException(name),
+                IDictionary dico => dico.Contains(name) ? dico[name] : throw new ArgumentOutOfRangeException(name),
                 IList => throw new NotNameableContextObjectException(Value),
                 _ => retrieveObjectProperty(name),
             };
 
             object? retrieveObjectProperty(string name)
                 => TryRetrieveObjectProperty(name, out var value)
                     ? value
-                    : throw new ArgumentOutOfRangeException(name);
+                    : throw new ArgumentException($"Cannot find a property named '{name}' in the object of type '{Value?.GetType().Name ?? "null"}'.");
         }
     }
 
@@ -60,6 +62,7 @@ public bool Contains(int index)
         => Value switch
         {
             DataRow row => index < row.Table.Columns.Count,
+            IReadOnlyDataRow row => index < row.ColumnsCount,
             IList list => index < list.Count,
             _ => throw new NotIndexableContextObjectException(Value)
         };
@@ -71,6 +74,7 @@ public object? this[int index]
             return Value switch
             {
                 DataRow row => index < row.Table.Columns.Count ? row[index] : throw new ArgumentOutOfRangeException(index.ToString()),
+                IReadOnlyDataRow row => index < row.ColumnsCount ? row[index] : throw new ArgumentOutOfRangeException(index.ToString()),
                 IList list => list[index],
                 _ => throw new NotIndexableContextObjectException(Value)
             };

Expressif/Values/IReadOnlyDataRow.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Expressif.Values;
+public interface IReadOnlyDataRow
+{
+    int ColumnsCount { get; }
+    bool ContainsColumn(string columnName);
+    object? this[string columnName] { get; }
+    object? this[int index] { get; }
+}