test for parameter file reader

api/tests/opentrons/protocols/parameters/test_parameter_file_reader.py

@@ -0,0 +1,26 @@
+import pytest
+from pathlib import Path
+from tempfile import NamedTemporaryFile
+
+from opentrons.protocols.parameters.exceptions import RuntimeParameterRequired
+from opentrons.protocols.parameters import parameter_file_reader as subject
+
+
+def test_open_file_path() -> None:
+    """It should open a temporary file handler given a path."""
+    with NamedTemporaryFile("r+") as file_to_open:
+        file_to_open.write("Hello World\n")
+        file_to_open.flush()
+
+        result = subject.open_file_path(Path(file_to_open.name))
+
+        assert result.readable()
+        assert not result.writable()
+        assert result.read() == "Hello World\n"
+        result.close()
+
+
+def test_open_file_path_raises() -> None:
+    """It should raise of no file path is provided."""
+    with pytest.raises(RuntimeParameterRequired):
+        subject.open_file_path(None)