Added tests for the time stopping callback (#1543)

* Added tests for time stopping.

* Small refactoring.

* Rename.

* Refactoring.

* Calming the angry bazel.

* Added the dependency to optimizers.

Author: gabrieldemarmiesse

tensorflow_addons/callbacks/time_stopping_test.py

@@ -0,0 +1,69 @@
+import time
+
+import pytest
+import numpy as np
+import tensorflow as tf
+from tensorflow.keras.models import Sequential
+from tensorflow.keras.layers import Dense
+
+from tensorflow_addons.callbacks.time_stopping import TimeStopping
+
+
+class SleepLayer(tf.keras.layers.Layer):
+    def __init__(self, secs):
+        self.secs = secs
+        super().__init__(dynamic=True)
+
+    def call(self, inputs):
+        time.sleep(self.secs)
+        return inputs
+
+
+def get_data_and_model(secs):
+    X = np.array([[0, 0], [0, 1], [1, 0], [1, 1]])
+    y = np.array([[0], [1], [1], [0]])
+
+    model = Sequential()
+    model.add(SleepLayer(secs))
+    model.add(Dense(1))
+    model.compile(loss="mean_squared_error")
+
+    # In case there is some initialization going on.
+    model.fit(X, y, epochs=1, verbose=0)
+    return X, y, model
+
+
+def test_stop_at_the_right_time():
+    X, y, model = get_data_and_model(0.1)
+
+    time_stopping = TimeStopping(2, verbose=0)
+    history = model.fit(X, y, epochs=30, verbose=0, callbacks=[time_stopping])
+
+    assert len(history.epoch) <= 20
+
+
+def test_default_value():
+    X, y, model = get_data_and_model(0.1)
+
+    time_stopping = TimeStopping()
+    history = model.fit(X, y, epochs=15, verbose=0, callbacks=[time_stopping])
+
+    assert len(history.epoch) == 15
+
+
+@pytest.mark.parametrize("verbose", [0, 1])
+def test_time_stopping_verbose(capsys, verbose):
+    X, y, model = get_data_and_model(0.25)
+
+    time_stopping = TimeStopping(1, verbose=verbose)
+
+    capsys.readouterr()  # flush the stdout/stderr buffer.
+    history = model.fit(X, y, epochs=10, verbose=0, callbacks=[time_stopping])
+    fit_stdout = capsys.readouterr().out
+    nb_epochs_run = len(history.epoch)
+    message = "Timed stopping at epoch " + str(nb_epochs_run)
+    if verbose:
+        assert message in fit_stdout
+    else:
+        assert message not in fit_stdout
+    assert len(history.epoch) <= 4