Improve testing of tf.bool in tf.unstack op.

Previously randn()'s results were cast to np.bool resuling in
True being the only value often. Also, check both the 0th and the -1th axis.

PiperOrigin-RevId: 308109624
Change-Id: I2b1b8bc6e6111874ad6f33c634d4d8a85c444882

tensorflow/python/kernel_tests/unstack_op_test.py

@@ -39,22 +39,49 @@ def np_split_squeeze(array, axis):
 
 class UnstackOpTest(test.TestCase):
 
+  def randn(self, shape, dtype):
+    data = np.random.randn(*shape)
+    if dtype == np.bool:
+      return data < 0  # Naive casting yields True with P(1)!
+    else:
+      return data.astype(dtype)
+
+  def unstackReference(self, data, axis):
+    """Use numpy primitives to implement unstack equivalent."""
+    result = []
+    rank = len(data.shape)
+    axis = axis + rank if axis < 0 else axis
+    for k in range(data.shape[axis]):
+      axis = rank + axis if axis < 0 else axis
+      # Slice in axis dimension of k'th slice.
+      # e.g. if rank=4 k=2, axis=2 then equivalent of data[:,:,2,:]
+      # Give error with loop context
+      slice_spec = tuple(
+          slice(None) if i != axis else k for i in range(rank))
+      result.append(data.__getitem__(slice_spec))
+    return result
+
   def testSimple(self):
     np.random.seed(7)
     for shape in (2,), (3,), (2, 3), (3, 2), (4, 3, 2):
-      for dtype in [
-          np.bool, np.float16, np.float32, np.float64, np.uint8, np.int32,
-          np.int64
-      ]:
-        data = np.random.randn(*shape).astype(dtype)
-        # Convert data to a single tensorflow tensor
-        x = constant_op.constant(data)
-        # Unstack into a list of tensors
-        cs = array_ops.unstack(x, num=shape[0])
-        self.assertEqual(type(cs), list)
-        self.assertEqual(len(cs), shape[0])
-        cs = [self.evaluate(c) for c in cs]
-        self.assertAllEqual(cs, data)
+      rank = len(shape)
+      for axis in range(-rank, rank):
+        for dtype in [
+            np.bool, np.float16, np.float32, np.float64, np.uint8, np.int32,
+            np.int64
+        ]:
+          data = self.randn(shape, dtype)
+          # Convert data to a single tensorflow tensor
+          x = constant_op.constant(data)
+
+          # Unstack into a list of tensors
+          ref = self.unstackReference(data, axis)
+          cs = array_ops.unstack(x, axis=axis)
+          self.assertEqual(type(cs), list)
+          self.assertEqual(len(cs), shape[axis])
+          for k, c in enumerate(cs):
+            with self.subTest(shape=shape, k=k, axis=axis, dtype=dtype):
+              self.assertAllEqual(ref[k], self.evaluate(c))
 
   def testSimpleGpu(self):
     if not test_util.is_gpu_available():
@@ -63,19 +90,24 @@ class UnstackOpTest(test.TestCase):
     np.random.seed(7)
     with test_util.force_gpu():
       for shape in (2,), (3,), (2, 3), (3, 2), (4, 3, 2):
-        for dtype in [
-            np.bool, np.float16, np.float32, np.float64, np.uint8, np.int32,
-            np.int64
-        ]:
-          data = np.random.randn(*shape).astype(dtype)
-          # Convert data to a single tensorflow tensor
-          x = constant_op.constant(data)
-          # Unstack into a list of tensors
-          cs = array_ops.unstack(x, num=shape[0])
-          self.assertEqual(type(cs), list)
-          self.assertEqual(len(cs), shape[0])
-          cs = [self.evaluate(c) for c in cs]
-          self.assertAllEqual(cs, data)
+        rank = len(shape)
+        for axis in range(-rank, rank):
+          for dtype in [
+              np.bool, np.float16, np.float32, np.float64, np.uint8, np.int32,
+              np.int64
+          ]:
+            data = self.randn(shape, dtype)
+            # Convert data to a single tensorflow tensor
+            x = constant_op.constant(data)
+            # Unstack into a list of tensors
+            ref = self.unstackReference(data, axis)
+            cs = array_ops.unstack(x, axis=axis)
+            self.assertEqual(type(cs), list)
+            self.assertEqual(len(cs), shape[axis])
+            for k, c in enumerate(cs):
+              # Give error with loop context
+              with self.subTest(shape=shape, k=k, axis=axis, dtype=dtype):
+                self.assertAllEqual(ref[k], self.evaluate(c))
 
   @test_util.run_deprecated_v1
   def testGradientsAxis0(self):