fix(BaseModel): don't suppress error if exe not found (#1901)

* warn at init/load time if exe not found, raise error at model run time

autotest/test_mbase.py

@@ -18,7 +18,7 @@ def mf6_model_path(example_data_path):
 
 @requires_exe("mf6")
 @pytest.mark.parametrize("use_ext", [True, False])
-def test_resolve_exe_named(function_tmpdir, use_ext):
+def test_resolve_exe_by_name(function_tmpdir, use_ext):
     if use_ext and system() != "Windows":
         pytest.skip(".exe extensions are Windows-only")
 
@@ -31,7 +31,7 @@ def test_resolve_exe_named(function_tmpdir, use_ext):
 
 @requires_exe("mf6")
 @pytest.mark.parametrize("use_ext", [True, False])
-def test_resolve_exe_full_path(function_tmpdir, use_ext):
+def test_resolve_exe_by_abs_path(function_tmpdir, use_ext):
     if use_ext and system() != "Windows":
         pytest.skip(".exe extensions are Windows-only")
 
@@ -44,7 +44,8 @@ def test_resolve_exe_full_path(function_tmpdir, use_ext):
 
 @requires_exe("mf6")
 @pytest.mark.parametrize("use_ext", [True, False])
-def test_resolve_exe_rel_path(function_tmpdir, use_ext):
+@pytest.mark.parametrize("forgive", [True, False])
+def test_resolve_exe_by_rel_path(function_tmpdir, use_ext, forgive):
     if use_ext and system() != "Windows":
         pytest.skip(".exe extensions are Windows-only")
 
@@ -66,9 +67,13 @@ def test_resolve_exe_rel_path(function_tmpdir, use_ext):
         assert actual.lower() == expected
         assert which(actual)
 
-        # should raise an error if exe DNE
-        with pytest.raises(FileNotFoundError):
-            resolve_exe("../bin/mf2005")
+        # check behavior if exe DNE
+        with (
+            pytest.warns(UserWarning)
+            if forgive
+            else pytest.raises(FileNotFoundError)
+        ):
+            assert not resolve_exe("../bin/mf2005", forgive)
 
 
 def test_run_model_when_namefile_not_in_model_ws(

autotest/test_modflow.py

@@ -200,6 +200,56 @@ def test_mt_modelgrid(function_tmpdir):
     assert np.array_equal(swt.modelgrid.idomain, ml.modelgrid.idomain)
 
 
+@requires_exe("mp7")
+def test_exe_selection(example_data_path, function_tmpdir):
+    model_path = example_data_path / "freyberg"
+    namfile_path = model_path / "freyberg.nam"
+
+    # no selection defaults to mf2005
+    exe_name = "mf2005"
+    assert Path(Modflow().exe_name).name == exe_name
+    assert Path(Modflow(exe_name=None).exe_name).name == exe_name
+    assert (
+        Path(Modflow.load(namfile_path, model_ws=model_path).exe_name).name
+        == exe_name
+    )
+    assert (
+        Path(
+            Modflow.load(
+                namfile_path, exe_name=None, model_ws=model_path
+            ).exe_name
+        ).name
+        == exe_name
+    )
+
+    # user-specified (just for testing - there is no legitimate reason
+    # to use mp7 with Modflow but Modpath7 derives from BaseModel too)
+    exe_name = "mp7"
+    assert Path(Modflow(exe_name=exe_name).exe_name).name == exe_name
+    assert (
+        Path(
+            Modflow.load(
+                namfile_path, exe_name=exe_name, model_ws=model_path
+            ).exe_name
+        ).name
+        == exe_name
+    )
+
+    # init/load should warn if exe DNE
+    exe_name = "not_an_exe"
+    with pytest.warns(UserWarning):
+        ml = Modflow(exe_name=exe_name)
+    with pytest.warns(UserWarning):
+        ml = Modflow.load(namfile_path, exe_name=exe_name, model_ws=model_path)
+
+    # run should error if exe DNE
+    ml = Modflow.load(namfile_path, exe_name=exe_name, model_ws=model_path)
+    ml.change_model_ws(function_tmpdir)
+    ml.write_input()
+    with pytest.raises(ValueError):
+        ml.run_model()
+
+
 def test_free_format_flag(function_tmpdir):
     Lx = 100.0
     Ly = 100.0

flopy/mbase.py

@@ -41,15 +41,21 @@
 iprn = -1
 
 
-def resolve_exe(exe_name: Union[str, os.PathLike]) -> str:
+def resolve_exe(
+    exe_name: Union[str, os.PathLike], forgive: bool = False
+) -> str:
     """
-    Resolves the absolute path of the executable.
+    Resolves the absolute path of the executable, raising FileNotFoundError if the executable
+    cannot be found (set forgive to True to return None and warn instead of raising an error).
 
     Parameters
     ----------
     exe_name : str or PathLike
         The executable's name or path. If only the name is provided,
         the executable must be on the system path.
+    forgive : bool
+        If True and executable cannot be found, return None and warn
+        rather than raising a FileNotFoundError. Defaults to False.
 
     Returns
     -------
@@ -75,6 +81,12 @@ def resolve_exe(exe_name: Union[str, os.PathLike]) -> str:
             # try tilde-expanded abspath without .exe suffix
             exe = which(Path(exe_name[:-4]).expanduser().absolute())
     if exe is None:
+        if forgive:
+            warn(
+                f"The program {exe_name} does not exist or is not executable."
+            )
+            return None
+
         raise FileNotFoundError(
             f"The program {exe_name} does not exist or is not executable."
         )
@@ -376,10 +388,11 @@ def __init__(
         self._namefile = self.__name + "." + self.namefile_ext
         self._packagelist = []
         self.heading = ""
-        try:
-            self.exe_name = resolve_exe(exe_name)
-        except:
-            self.exe_name = "mf2005"
+        self.exe_name = (
+            "mf2005"
+            if exe_name is None
+            else resolve_exe(exe_name, forgive=True)
+        )
         self._verbose = verbose
         self.external_path = None
         self.external_extension = "ref"