Clarify behavior of fit/predict/evaluate when inputs are Datasets and step args are None.

PiperOrigin-RevId: 235238247

tensorflow/python/keras/engine/training.py

@@ -637,11 +637,15 @@ class Model(Network):
             next epoch. When training with input tensors such as
             TensorFlow data tensors, the default `None` is equal to
             the number of samples in your dataset divided by
-            the batch size, or 1 if that cannot be determined.
+            the batch size, or 1 if that cannot be determined. If x is a
+            `tf.data` dataset or a dataset iterator, and 'steps_per_epoch'
+            is None, the epoch will run until the input dataset is exhausted.
         validation_steps: Only relevant if `validation_data` is provided and
             is a dataset or dataset iterator. Total number of steps (batches of
             samples) to draw before stopping when performing validation
-            at the end of every epoch.
+            at the end of every epoch. If validation_data is a `tf.data` dataset
+            or a dataset iterator, and 'validation_steps' is None, validation
+            will run until the `validation_data` dataset is exhausted.
         validation_freq: Only relevant if validation data is provided. Integer
             or `collections.Container` instance (e.g. list, tuple, etc.). If an
             integer, specifies how many training epochs to run before a new
@@ -926,6 +930,8 @@ class Model(Network):
             Total number of steps (batches of samples)
             before declaring the evaluation round finished.
             Ignored with the default value of `None`.
+            If x is a `tf.data` dataset or a dataset iterator, and `steps` is
+            None, 'evaluate' will run until the dataset is exhausted.
         callbacks: List of `keras.callbacks.Callback` instances.
             List of callbacks to apply during evaluation.
             See [callbacks](/api_docs/python/tf/keras/callbacks).
@@ -1074,7 +1080,9 @@ class Model(Network):
         verbose: Verbosity mode, 0 or 1.
         steps: Total number of steps (batches of samples)
             before declaring the prediction round finished.
-            Ignored with the default value of `None`.
+            Ignored with the default value of `None`. If x is a `tf.data`
+            dataset or a dataset iterator, and `steps` is None, `predict` will
+            run until the input dataset is exhausted.
         callbacks: List of `keras.callbacks.Callback` instances.
             List of callbacks to apply during prediction.
             See [callbacks](/api_docs/python/tf/keras/callbacks).