From 2918494f3731bbf58697f635127de66df63b5273 Mon Sep 17 00:00:00 2001
From: Joshua Larsen <jlarsen@usgs.gov>
Date: Mon, 16 Aug 2021 18:33:04 -0700
Subject: [PATCH] Fix(MF6Output): fix add new obs package issue

* update MF6Output gwt list() method to use MfListBudget
* Added test to t504_test.py for adding new observations
---
 autotest/t504_test.py          | 35 ++++++++++++++++++++++++++++++++++
 flopy/mf6/utils/output_util.py | 29 ++++++++++++++++++++++------
 2 files changed, 58 insertions(+), 6 deletions(-)

diff --git a/autotest/t504_test.py b/autotest/t504_test.py
index 57798d0e44..8e5b42ca8a 100644
--- a/autotest/t504_test.py
+++ b/autotest/t504_test.py
@@ -1235,6 +1235,40 @@ def test_mf6_output():
         raise AssertionError()
 
 
+def test_mf6_output_add_observation():
+    model_name = "lakeex2a"
+    sim_ws = os.path.join("..", "examples", "data", "mf6", "test045_lake2tr")
+    sim = flopy.mf6.MFSimulation.load(sim_ws=sim_ws, exe_name=exe_name)
+    gwf = sim.get_model(model_name)
+
+    # remove sfr_obs and add a new sfr obs
+    sfr = gwf.sfr
+
+    obs_file = "{}.sfr.obs".format(model_name)
+    csv_file = obs_file + ".csv"
+    obs_dict = {
+        csv_file: [
+            ("l08_stage", "stage", (8,)),
+            ("l09_stage", "stage", (9,)),
+            ("l14_stage", "stage", (14,)),
+            ("l15_stage", "stage", (15,)),
+        ]
+    }
+    gwf.sfr.obs.initialize(
+        filename=obs_file, digits=10, print_input=True, continuous=obs_dict
+    )
+
+    sim.simulation_data.mfpath.set_sim_path(cpth)
+    sim.write_simulation()
+    sim.run_simulation()
+
+    # check that .output finds the newly added OBS package
+    sfr_obs = gwf.sfr.output.obs()
+
+    if not isinstance(sfr_obs, flopy.utils.Mf6Obs):
+        raise TypeError("remove and add observation test (Mf6Output) failed")
+
+
 if __name__ == "__main__":
     test001a_tharmonic()
     test001e_uzf_3lay()
@@ -1249,3 +1283,4 @@ def test_mf6_output():
     test_cbc_precision()
     test_replace_ims_package()
     test_mf6_output()
+    test_mf6_output_add_observation()
diff --git a/flopy/mf6/utils/output_util.py b/flopy/mf6/utils/output_util.py
index a73ce3e850..900aaf9e55 100644
--- a/flopy/mf6/utils/output_util.py
+++ b/flopy/mf6/utils/output_util.py
@@ -6,7 +6,6 @@
     ZoneBudget6,
     ZoneFile6,
     MfListBudget,
-    MtListBudget,
 )
 from ...utils.observationfile import CsvFile
 from ...pakbase import PackageInterface
@@ -101,6 +100,28 @@ def __init__(self, obj):
                                         if str(ky[-2]).lower() == "fileout":
                                             data = [[ky[-1]]]
                                             break
+                                        elif (
+                                            str(ky[-3]) == "continuous"
+                                            and str(ky[-1]) == "output"
+                                        ):
+                                            if (
+                                                obj._simulation_data.mfdata[
+                                                    ky
+                                                ].array[0][0]
+                                                == "fileout"
+                                            ):
+                                                data = [
+                                                    [
+                                                        obj._simulation_data.mfdata[
+                                                            ky
+                                                        ].array[
+                                                            0
+                                                        ][
+                                                            -2
+                                                        ]
+                                                    ]
+                                                ]
+                                                break
 
                             if rectype == "package_convergence":
                                 rectype = "csv"
@@ -301,13 +322,9 @@ def __list(self):
             MfListBudget, MtListBudget object
         """
         if self._lst is not None:
-            reader = MfListBudget
-            if self._mtype == "gwt":
-                reader = MtListBudget
-
             try:
                 list_file = os.path.join(self._sim_ws, self._lst)
-                return reader(list_file)
+                return MfListBudget(list_file)
             except (AssertionError, IOError, FileNotFoundError):
                 return None