Add a bit of a test suite

Author: alanhdu

tests/fail/random.py

@@ -0,0 +1,8 @@
+import numpy as np
+
+np.random.RandomState(b"hello")  # E: incompatible type
+np.random.RandomState("")  # E: incompatible type
+
+np.random.beta(3)  # E: No overload variant
+np.random.beta(3, "hello")  # E: incompatible type
+np.random.beta(3, 4, "hello")  # E: incompatible type

tests/pass/random.py

@@ -0,0 +1,5 @@
+import numpy as np
+
+state = np.random.RandomState()
+state = np.random.RandomState(3)
+state = np.random.RandomState([3])

tests/reveal/random.py

@@ -0,0 +1,4 @@
+import numpy as np
+
+np.random.beta(3, 4.0)  # E: float
+np.random.beta(3.0, 4.0, size=[3, 4])  # E: ndarray