test(loaders): Add test for load_travel_times #125 (#169)

* test(loaders): Add test for load_travel_times #125
* Add unittest coverage for loaders.py load_travel_times()
* Issue -> #125

* * Reverted changes to config.yaml
* Split test_load_travel_times() into 2 smaller unittests

* * Refactor repeated code blocks into single helper function. Following DRY.

tests/test_loaders.py

@@ -1,23 +1,47 @@
-from typing import Any, Dict
+from typing import Any, Dict, List
 
 import pandas as pd
 import pytest
-from pandas import DataFrame, read_csv
+from pandas import DataFrame, concat, read_csv
 from pandas.api.types import is_float_dtype
 
 from gnatss.configs.main import Configuration
-from gnatss.constants import GPS_COV, GPS_GEOCENTRIC, GPS_TIME, SP_DEPTH, SP_SOUND_SPEED
-from gnatss.loaders import load_configuration, load_gps_solutions, load_sound_speed
+from gnatss.constants import (
+    GPS_COV,
+    GPS_GEOCENTRIC,
+    GPS_TIME,
+    SP_DEPTH,
+    SP_SOUND_SPEED,
+    TT_DATE,
+    TT_TIME,
+)
+from gnatss.loaders import (
+    load_configuration,
+    load_gps_solutions,
+    load_sound_speed,
+    load_travel_times,
+)
 from gnatss.main import gather_files
 from tests import TEST_DATA_FOLDER
 
+PARSED_FILE = "parsed"
+
 
 @pytest.fixture
 def all_files_dict() -> Dict[str, Any]:
     config = load_configuration(TEST_DATA_FOLDER / "config.yaml")
     return gather_files(config)
 
 
+@pytest.fixture
+def all_files_dict_j2k_travel_times() -> Dict[str, Any]:
+    config = load_configuration(TEST_DATA_FOLDER / "config.yaml")
+    config.solver.input_files.travel_times.path = (
+        "./tests/data/2022/NCL1/**/WG_*/pxp_tt_j2k"
+    )
+    return gather_files(config)
+
+
 @pytest.mark.parametrize(
     "config_yaml_path",
     [None, TEST_DATA_FOLDER / "invalid_config.yaml"],
@@ -44,6 +68,111 @@ def test_load_sound_speed(all_files_dict):
     assert is_float_dtype(svdf[SP_DEPTH]) and is_float_dtype(svdf[SP_SOUND_SPEED])
 
 
+@pytest.fixture
+def transponder_ids() -> List[str]:
+    config = load_configuration(TEST_DATA_FOLDER / "config.yaml")
+    transponders = config.solver.transponders
+    return [t.pxp_id for t in transponders]
+
+
+def _load_travel_times_pass_testcase_helper(
+    expected_columns, travel_times, transponder_ids, is_j2k, time_scale
+):
+    loaded_travel_times = load_travel_times(
+        files=travel_times,
+        transponder_ids=transponder_ids,
+        is_j2k=is_j2k,
+        time_scale=time_scale,
+    )
+
+    # raw_travel_times contains the expected df
+    raw_travel_times = concat(
+        [
+            read_csv(i, delim_whitespace=True, header=None)
+            for i in travel_times
+            if PARSED_FILE not in i
+        ]
+    ).reset_index(drop=True)
+
+    column_num_diff = len(expected_columns) - len(raw_travel_times.columns)
+    if column_num_diff < 0:
+        raw_travel_times = raw_travel_times.iloc[:, :column_num_diff]
+    raw_travel_times.columns = expected_columns
+
+    if not is_j2k:
+        raw_travel_times = raw_travel_times.drop([TT_DATE], axis=1)
+
+    # Assert that df returned from "loaded_travel_times()" matches parameters of expected df
+    assert isinstance(loaded_travel_times, DataFrame)
+    assert all(
+        is_float_dtype(loaded_travel_times[column])
+        for column in [*transponder_ids, TT_TIME]
+    )
+    assert loaded_travel_times.shape == raw_travel_times.shape
+    assert set(loaded_travel_times.columns.values.tolist()) == set(
+        raw_travel_times.columns.values.tolist()
+    )
+
+    # Verify microsecond to second conversion for each transponder_id column
+    assert loaded_travel_times[transponder_ids].equals(
+        raw_travel_times[transponder_ids].apply(lambda x: x * 1e-6)
+    )
+
+
+@pytest.mark.parametrize(
+    "is_j2k, time_scale",
+    [(True, "tt"), (False, "tt")],
+)
+def test_load_j2k_travel_times(
+    transponder_ids, all_files_dict_j2k_travel_times, is_j2k, time_scale
+):
+    if not is_j2k:
+        # load_travel_times() should raise Exception
+        # if called with is_j2k=False on j2k type travel time files
+        with pytest.raises(AttributeError):
+            _ = load_travel_times(
+                files=all_files_dict_j2k_travel_times["travel_times"],
+                transponder_ids=transponder_ids,
+                is_j2k=is_j2k,
+                time_scale=time_scale,
+            )
+    else:
+        expected_columns = [TT_TIME, *transponder_ids]
+        _load_travel_times_pass_testcase_helper(
+            expected_columns,
+            all_files_dict_j2k_travel_times["travel_times"],
+            transponder_ids,
+            is_j2k,
+            time_scale,
+        )
+
+
+@pytest.mark.parametrize(
+    "is_j2k, time_scale",
+    [(True, "tt"), (False, "tt")],
+)
+def test_load_non_j2k_travel_times(transponder_ids, all_files_dict, is_j2k, time_scale):
+    if is_j2k:
+        # load_travel_times() should raise Exception
+        # if called with is_j2k=True on non-j2k type travel time files
+        with pytest.raises(TypeError):
+            _ = load_travel_times(
+                files=all_files_dict["travel_times"],
+                transponder_ids=transponder_ids,
+                is_j2k=is_j2k,
+                time_scale=time_scale,
+            )
+    else:
+        expected_columns = [TT_DATE, TT_TIME, *transponder_ids]
+        _load_travel_times_pass_testcase_helper(
+            expected_columns,
+            all_files_dict["travel_times"],
+            transponder_ids,
+            is_j2k,
+            time_scale,
+        )
+
+
 @pytest.mark.parametrize(
     "time_round",
     [3, 6],