Drop support for Python 3.6, 3.7, 3.8, 3.9.

These older Python versions have reached end of life, no longer receive
even security fixes. What hurts us more, however, is that modern dev
tools, such as UV and Ruff, are not aware of Python 3.6, and thus
require work-arounds to include it.

Author: john-hen

mph/client.py

@@ -13,8 +13,9 @@
 from pathlib import Path
 from logging import getLogger
 
-from typing import overload, Iterator
-from jpype  import JClass
+from typing          import overload
+from collections.abc import Iterator
+from jpype           import JClass
 
 
 # The following look-up table is used by the `modules()` method. It is

mph/discovery.py

@@ -245,9 +245,8 @@ def search_path() -> Path | None:
         process = subprocess.run(
             command, shell=True, check=True, timeout=3,
             stdout=subprocess.PIPE, stderr=subprocess.DEVNULL,
-            universal_newlines=True, encoding='UTF-8',
+            text=True, encoding='UTF-8',
         )
-        # `universal_newlines` instead of `text` to support Python 3.6.
     except subprocess.CalledProcessError:
         log.debug('Command exited with an error.')
         return
@@ -376,14 +375,12 @@ def find_backends() -> list[Backend]:
         # Get version information from Comsol server.
         command: list[Path | str]
         command = server + ['--version']
-        command[0] = str(command[0])   # Needed to support Python 3.6 and 3.7.
         try:
             arguments = dict(          # noqa: C408 (unnecessary `dict()` call)
                 check=True, timeout=15,
                 stdout=subprocess.PIPE, stderr=subprocess.DEVNULL,
-                universal_newlines=True, encoding='ascii', errors='ignore',
+                text=True, encoding='ascii', errors='ignore',
             )
-            # `universal_newlines` instead of `text` to support Python 3.6.
             if system == 'Windows':
                 arguments['creationflags'] = 0x08000000
             process = subprocess.run(

mph/model.py

@@ -10,10 +10,11 @@
 from re       import match
 from logging  import getLogger
 
-from jpype        import JClass
-from typing       import overload, Literal, Iterator
-from numpy.typing import ArrayLike, NDArray
-from numpy        import int32, float64
+from jpype           import JClass
+from typing          import overload, Literal
+from collections.abc import Iterator
+from numpy.typing    import ArrayLike, NDArray
+from numpy           import int32, float64
 
 
 # The following look-up table is used by the `modules()` method. It maps

mph/node.py

@@ -11,11 +11,12 @@
 from functools import lru_cache
 from logging   import getLogger
 
-from typing       import TYPE_CHECKING, overload, Iterator, Sequence, Literal
-from numpy.typing import ArrayLike, NDArray
-from numpy        import int32
+from typing          import TYPE_CHECKING, overload, Literal
+from collections.abc import Iterator, Sequence
+from numpy.typing    import ArrayLike, NDArray
+from numpy           import int32
 if TYPE_CHECKING:
-    from .model   import Model
+    from .model      import Model
 
 
 log = getLogger(__package__)

mph/server.py

@@ -106,7 +106,6 @@ def __init__(self,
                 log.error(error)
                 raise ValueError(error)
         command = server + arguments + extra_arguments
-        command[0] = str(command[0])   # Required for Python 3.6 and 3.7.
         process = start(command, stdin=PIPE, stdout=PIPE, errors='ignore')
 
         # Remember the requested port (if any).

pyproject.toml

@@ -64,7 +64,7 @@ name = 'mph'
 [tool.ruff]
 line-length    = 79
 indent-width   = 4
-target-version = 'py37'
+target-version = 'py310'
 include = [
     'mph/*.py',
     'tests/*.py',
@@ -119,8 +119,6 @@ include = [
         'PT012',              # `pytest.raises()` with multiple statements
         'PT013',              # incorrect pytest import
         'PTH201',             # Never use `Path('.')`.
-        'UP021',              # `universal_newlines` instead of `text`
-        'UP022',              # `PIPE` instead of `capture_output`
         'UP024',              # Replace `IOError` with `OSError`.
     ]
 

tests/test_exit.py

@@ -2,21 +2,20 @@
 
 from fixtures   import setup_logging
 
-from subprocess import run, PIPE
+from subprocess import run
 from pathlib    import Path
 from sys        import executable as python
 
 
-def run_script(name):
+def run_script(name: str):
     # Runs the named script from the project's root folder so that coverage
     # reporting doesn't get confused about source file locations.
     here = Path(__file__).resolve().parent
     file = here/name
     assert file.is_file()
     assert file.suffix == '.py'
     root = here.parent
-    process = run([python, str(file)], cwd=root,
-                  stdout=PIPE, stderr=PIPE, universal_newlines=True)
+    process = run([python, file], cwd=root, capture_output=True, text=True)
     return process