Make changes to tests as discussed in Issue #405

pyani/versiondb.py

@@ -31,13 +31,20 @@ def get_version(alembic_exe: Path = pyani_config.ALEMBIC_DEFAULT) -> str:
 
     The following circumstances are explicitly reported as strings:
 
+    - a value of None given for the executable
     - no executable at passed path
     - non-executable file at passed path (this includes cases where the user doesn't have execute permissions on the file)
     - no version info returned
     """
 
     try:
-        alembic_path = Path(shutil.which(alembic_exe))  # type:ignore
+        # Returns a TypeError if `alembic_exe` is None
+        try:
+            alembic_path = shutil.which(alembic_exe)  # type:ignore
+        except TypeError:
+            return f"expected path to alembic executable; received {alembic_exe}"
+        # Returns a TypeError if `alembic_path` is not on the PATH
+        alembic_path = Path(alembic_path)
     except TypeError:
         return f"{alembic_exe} is not found in $PATH"
 

tests/test_versiondb.py

@@ -41,33 +41,44 @@ def test_get_version_nonetype():
     """Test behaviour when no location for the executable is given."""
     test_file_0 = None
 
-    assert versiondb.get_version(test_file_0) == f"{test_file_0} is not found in $PATH"
+    assert (
+        versiondb.get_version(test_file_0)
+        == f"expected path to alembic executable; received {test_file_0}"
+    )
+
+
+# Test case 1: no such file exists
+def test_get_version_random_string():
+    """Test behaviour when the given 'file' is not one."""
+    test_file_1 = "string"
 
+    assert versiondb.get_version(test_file_1) == f"{test_file_1} is not found in $PATH"
 
-# Test case 1: there is no executable
+
+# Test case 2: there is no executable
 def test_get_version_no_exe(executable_missing, monkeypatch):
     """Test behaviour when there is no file at the specified executable location."""
-    test_file_1 = Path("/non/existent/alembic")
-    assert versiondb.get_version(test_file_1) == f"No alembic at {test_file_1}"
+    test_file_2 = Path("/non/existent/alembic")
+    assert versiondb.get_version(test_file_2) == f"No alembic at {test_file_2}"
 
 
-# Test case 2: there is a file, but it is not executable
+# Test case 3: there is a file, but it is not executable
 def test_get_version_exe_not_executable(executable_not_executable, monkeypatch):
     """Test behaviour when the file at the executable location is not executable."""
-    test_file_2 = Path("/non/executable/alembic")
+    test_file_3 = Path("/non/executable/alembic")
     assert (
-        versiondb.get_version(test_file_2)
-        == f"alembic exists at {test_file_2} but not executable"
+        versiondb.get_version(test_file_3)
+        == f"alembic exists at {test_file_3} but not executable"
     )
 
 
-# Test case 3: there is an executable file, but the version can't be retrieved
+# Test case 4: there is an executable file, but the version can't be retrieved
 def test_get_version_exe_no_version(executable_without_version, monkeypatch):
     """Test behaviour when the version for the executable can not be retrieved."""
-    test_file_3 = Path("/missing/version/alembic")
+    test_file_4 = Path("/missing/version/alembic")
     assert (
-        versiondb.get_version(test_file_3)
-        == f"alembic exists at {test_file_3} but could not retrieve version"
+        versiondb.get_version(test_file_4)
+        == f"alembic exists at {test_file_4} but could not retrieve version"
     )