add flink pipeline opts test

tests/unit/test_flink.py

@@ -0,0 +1,42 @@
+from typing import Optional
+from unittest.mock import patch
+
+import pytest
+
+from pangeo_forge_runner.bakery.flink import FlinkOperatorBakery
+
+
+@pytest.mark.parametrize("parallelism, max_parallelism", [(None, None), (100, 100)])
+def test_pipelineoptions(
+    parallelism: Optional[int],
+    max_parallelism: Optional[int],
+):
+    """
+    Quickly validate some of the PipelineOptions set
+    """
+    fob = FlinkOperatorBakery()
+    fob.parallelism = parallelism
+    fob.max_parallelism = max_parallelism
+
+    # FlinkOperatorBakery.get_pipeline_options calls `kubectl` in a subprocess,
+    # so we patch subprocess here to skip that behavior for this test
+    with patch("pangeo_forge_runner.bakery.flink.subprocess"):
+        po = fob.get_pipeline_options("job", "some-container:some-tag", {})
+        # some flink args, e.g. 'parallelism', are apparently 'unknown_options' from
+        # the perspective of PipelineOptions, so we retain those here for the test.
+        # it doesn't seem like their 'unknown' status prevents them from being passed to
+        # flink in an actual deployment, though.
+        opts = po.get_all_options(retain_unknown_options=True)
+
+    assert opts["flink_version"] == "1.15"
+
+    for optional_arg, value in dict(
+        parallelism=parallelism,
+        max_parallelism=max_parallelism,
+    ).items():
+        # if these args are not passed, we don't want them to appear in
+        # the pipeline opts, so we verify here that is actually happening.
+        if value is None:
+            assert optional_arg not in opts
+        else:
+            assert opts[optional_arg] == value