Pin tensorforce and add test

Author: rosbo

Dockerfile

@@ -371,7 +371,8 @@ RUN pip install flashtext && \
     pip install shap && \
     pip install ray && \
     pip install gym && \
-    pip install tensorforce && \
+    # b/167268016 tensorforce 0.6.6 has an explicit dependency on tensorflow 2.3.1 which is causing a downgrade.
+    pip install tensorforce==0.5.5 && \
     pip install pyarabic && \
     pip install pandasql && \
     pip install tensorflow_hub && \

tests/test_tensorforce.py

@@ -0,0 +1,30 @@
+import unittest
+
+from tensorforce import Agent, Environment
+
+class TestTensorforce(unittest.TestCase):
+    # based on https://github.com/tensorforce/tensorforce/tree/master#quickstart-example-code.
+    def test_quickstart(self):
+        environment = Environment.create(
+            environment='gym', level='CartPole', max_episode_timesteps=500
+        )
+
+        agent = Agent.create(
+            agent='tensorforce',
+            environment=environment,  # alternatively: states, actions, (max_episode_timesteps)
+            memory=1000,
+            update=dict(unit='timesteps', batch_size=32),
+            optimizer=dict(type='adam', learning_rate=3e-4),
+            policy=dict(network='auto'),
+            objective='policy_gradient',
+            reward_estimation=dict(horizon=1)
+        )
+
+        # Train for a single episode.
+        states = environment.reset()
+        actions = agent.act(states=states)
+        states, terminal, reward = environment.execute(actions=actions)
+
+        self.assertEqual(4, len(states))
+        self.assertFalse(terminal)
+        self.assertEqual(1, reward)