Add more checks and tests

ea384d9c5f1d2f370363f299d6a1328de08befcb
commit ea384d9c5f1d2f370363f299d6a1328de08befcb
diff --git a/src/embed_tests/TestPyBuffer.cs b/src/embed_tests/TestPyBuffer.cs
@@ -2,11 +2,14 @@
 using System.Runtime.CompilerServices;
 using System.Text;
 using System.Threading;
+
 using NUnit.Framework;
+
 using Python.Runtime;
 using Python.Runtime.Codecs;
 
-namespace Python.EmbeddingTest {
+namespace Python.EmbeddingTest
+{
     class TestPyBuffer
     {
         [OneTimeSetUp]
@@ -70,16 +73,37 @@ public void GetPointer()
 
             using PyBuffer buf = ndArray.GetBuffer(PyBUF.STRIDES);
 
-            // this throws System.ExecutionEngineException
             var ptr = buf.GetPointer([0, 0, 0]);
 
             Assert.That(ptr, Is.Not.EqualTo(IntPtr.Zero));
+
+            var ptrEnd = buf.GetPointer([9, 9, 9]);
+            Assert.That(ptrEnd, Is.Not.EqualTo(IntPtr.Zero));
+
+            Assert.Throws<ArgumentNullException>(() => buf.GetPointer(null!));
+
+            Assert.Throws<ArgumentOutOfRangeException>(() => buf.GetPointer([0, 0]));
+            Assert.Throws<ArgumentOutOfRangeException>(() => buf.GetPointer([0, 0, 0, 0]));
+
+            Assert.Throws<ArgumentOutOfRangeException>(() => buf.GetPointer([-1, 0, 0]));
+            Assert.Throws<ArgumentOutOfRangeException>(() => buf.GetPointer([0, -1, 0]));
+            Assert.Throws<ArgumentOutOfRangeException>(() => buf.GetPointer([0, 0, -1]));
+
+            Assert.Throws<ArgumentOutOfRangeException>(() => buf.GetPointer([10, 0, 0]));
+            Assert.Throws<ArgumentOutOfRangeException>(() => buf.GetPointer([0, 10, 0]));
+            Assert.Throws<ArgumentOutOfRangeException>(() => buf.GetPointer([0, 0, 10]));
+
+            using PyBuffer buf2 = ndArray.GetBuffer(PyBUF.ND);
+
+            Assert.Throws<InvalidOperationException>(
+                () => buf2.GetPointer([0, 0, 0])
+            );
         }
 
         [Test]
         public void ArrayHasBuffer()
         {
-            var array = new[,] {{1, 2}, {3,4}};
+            var array = new[,] { { 1, 2 }, { 3, 4 } };
             var memoryView = PythonEngine.Eval("memoryview");
             var mem = memoryView.Invoke(array.ToPython());
             Assert.That(mem[(0, 0).ToPython()].As<int>(), Is.EqualTo(1));
@@ -128,7 +152,7 @@ public void Finalization()
         [Test]
         public void MultidimensionalNumPyArray()
         {
-            var ndarray = np.arange(24).reshape(1,2,3,4).T;
+            var ndarray = np.arange(24).reshape(1, 2, 3, 4).T;
             PyObject ndim = ndarray.ndim;
             PyObject shape = ndarray.shape;
             PyObject strides = ndarray.strides;

diff --git a/src/runtime/PythonTypes/PyBuffer.cs b/src/runtime/PythonTypes/PyBuffer.cs
@@ -110,10 +110,37 @@ public bool IsContiguous(BufferOrderStyle order)
         /// </summary>
         public IntPtr GetPointer(long[] indices)
         {
-            if (indices is null) throw new ArgumentNullException(nameof(indices));
+            if (indices is null)
+                throw new ArgumentNullException(nameof(indices));
+
+            if (Strides is null)
+                throw new InvalidOperationException($"{nameof(GetPointer)} requires {nameof(Strides)} to be filled");
+
+            if (indices.Length != Dimensions)
+                throw new ArgumentOutOfRangeException($"{nameof(indices)} must be exactly {Dimensions} long");
+
+            if (Dimensions == 0 && Shape is null)
+                throw new InvalidOperationException($"{nameof(GetPointer)} requires {nameof(Shape)} to be filled for dimensional buffers");
+
             ThrowIfDisposed();
+
             if (Runtime.PyVersion < new Version(3, 7))
                 throw new NotSupportedException("GetPointer requires at least Python 3.7");
+
+            var indicesArr = new nint[Dimensions];
+
+            for (var i = 0; i < Dimensions; i++)
+            {
+                indicesArr[i] = checked((nint)indices[i]);
+
+                if (indicesArr[i] < 0 || indicesArr[i] >= Shape![i])
+                {
+                    throw new ArgumentOutOfRangeException(
+                        $"Index {i} has a value of {indicesArr[i]} not in [0, {Shape![i]})"
+                    );
+                }
+            }
+
             return Runtime.PyBuffer_GetPointer(ref _view, indices.Select(x => checked((nint)x)).ToArray());
         }