Added tests for identity matrix function (#18)

* Added tests for identity matrix function

* Fixed test_identity_invalid_shape() method

* Fixed import formatting, black and flake8 automatic checks

---------

Co-authored-by: Chaluvadi <[email protected]>

Author: sakchal

tests/test_identity.py

@@ -0,0 +1,70 @@
+import random
+
+import pytest
+
+import arrayfire_wrapper.dtypes as dtypes
+import arrayfire_wrapper.lib as wrapper
+
+
+@pytest.mark.parametrize(
+    "shape",
+    [
+        (),
+        (random.randint(1, 10), 1),
+        (random.randint(1, 10), random.randint(1, 10)),
+        (random.randint(1, 10), random.randint(1, 10), random.randint(1, 10)),
+        (random.randint(1, 10), random.randint(1, 10), random.randint(1, 10), random.randint(1, 10)),
+    ],
+)
+def test_identity_shape(shape: tuple) -> None:
+    """Test if identity creates an array with the correct shape"""
+    dtype = dtypes.s16
+
+    result = wrapper.identity(shape, dtype)
+
+    assert wrapper.get_dims(result)[0 : len(shape)] == shape  # noqa: E203
+
+
+def test_identity_invalid_shape() -> None:
+    """Test if identity handles a shape with greater than 4 dimensions"""
+    with pytest.raises(TypeError) as excinfo:
+        invalid_shape = (
+            random.randint(1, 10),
+            random.randint(1, 10),
+            random.randint(1, 10),
+            random.randint(1, 10),
+            random.randint(1, 10),
+        )
+        dtype = dtypes.s16
+
+        wrapper.identity(invalid_shape, dtype)
+
+    assert f"CShape.__init__() takes from 1 to 5 positional arguments but {len(invalid_shape) + 1} were given" in str(
+        excinfo.value
+    )
+
+
+def test_identity_nonsquare_shape() -> None:
+    dtype = dtypes.s16
+    shape = (5, 6)
+
+    result = wrapper.identity(shape, dtype)
+
+    assert wrapper.get_dims(result)[0 : len(shape)] == shape  # noqa: E203
+
+
+@pytest.mark.parametrize(
+    "dtype_index",
+    [i for i in range(13)],
+)
+def test_identity_dtype(dtype_index: int) -> None:
+    """Test if identity creates an array with the correct dtype"""
+    if dtype_index in [2, 3] and not wrapper.get_dbl_support():
+        pytest.skip()
+
+    shape = (5, 5)
+    dtype = dtypes.c_api_value_to_dtype(dtype_index)
+
+    result = wrapper.identity(shape, dtype)
+
+    assert dtypes.c_api_value_to_dtype(wrapper.get_type(result)) == dtype