Add more tests for JAX implementation of ChoiceRV

tests/link/jax/test_random.py

@@ -545,27 +545,49 @@ def test_random_dirichlet(parameter, size):
 
 
 def test_random_choice():
-    # Elements are picked at equal frequency
-    num_samples = 10000
+    # `replace=True` and `p is None`
     rng = shared(np.random.RandomState(123))
-    g = pt.random.choice(np.arange(4), size=num_samples, rng=rng)
+    g = pt.random.choice(np.arange(4), size=10_000, rng=rng)
+    g_fn = compile_random_function([], g, mode=jax_mode)
+    samples = g_fn()
+    assert samples.shape == (10_000,)
+    # Elements are picked at equal frequency
+    np.testing.assert_allclose(np.mean(samples == 3), 0.25, 2)
+
+    # `replace=True` and `p is not None`
+    rng = shared(np.random.default_rng(123))
+    g = pt.random.choice(4, p=np.array([0.0, 0.5, 0.0, 0.5]), size=(5, 2), rng=rng)
     g_fn = compile_random_function([], g, mode=jax_mode)
     samples = g_fn()
-    np.testing.assert_allclose(np.sum(samples == 3) / num_samples, 0.25, 2)
+    assert samples.shape == (5, 2)
+    # Only odd numbers are picked
+    assert np.all(samples % 2 == 1)
 
-    # `replace=False` produces unique results
+    # `replace=False` and `p is None`
     rng = shared(np.random.RandomState(123))
-    g = pt.random.choice(np.arange(100), replace=False, size=99, rng=rng)
+    g = pt.random.choice(np.arange(100), replace=False, size=(2, 49), rng=rng)
     g_fn = compile_random_function([], g, mode=jax_mode)
     samples = g_fn()
-    assert len(np.unique(samples)) == 99
+    assert samples.shape == (2, 49)
+    # Elements are unique
+    assert len(np.unique(samples)) == 98
 
-    # We can pass an array with probabilities
+    # `replace=False` and `p is not None`
     rng = shared(np.random.RandomState(123))
-    g = pt.random.choice(np.arange(3), p=np.array([1.0, 0.0, 0.0]), size=10, rng=rng)
+    g = pt.random.choice(
+        8,
+        p=np.array([0.25, 0, 0.25, 0, 0.25, 0, 0.25, 0]),
+        size=3,
+        rng=rng,
+        replace=False,
+    )
     g_fn = compile_random_function([], g, mode=jax_mode)
     samples = g_fn()
-    np.testing.assert_allclose(samples, np.zeros(10))
+    assert samples.shape == (3,)
+    # Elements are unique
+    assert len(np.unique(samples)) == 3
+    # Only even numbers are picked
+    assert np.all(samples % 2 == 0)
 
 
 def test_random_categorical():