[KED-1275] Simplify min_version and add import-linter to test_require…

…ments (kedro-org#358)

.pre-commit-config.yaml

@@ -106,7 +106,7 @@ repos:
             name: "Black"
             language: system
             pass_filenames: false
-            entry: python -m tools.min_version 3.6 "pip install black" "black kedro extras features tests"
+            entry: python -m tools.min_version 3.6 "black kedro extras features tests"
           - id: legal
             name: "Licence check"
             language: system
@@ -116,4 +116,4 @@ repos:
             name: "Import Linter"
             language: system
             pass_filenames: false
-            entry: python -m tools.min_version 3.6 "pip install import-linter" lint-imports
+            entry: python -m tools.min_version 3.6 lint-imports

test_requirements.txt

@@ -9,6 +9,7 @@ codacy-coverage
 flake8>=3.5,<4.0
 gcsfs>=0.3.0, <1.0
 hdfs>=2.5.8, <3.0
+import-linter==1.0; python_version >= '3.6'
 joblib==0.12.3
 jupyter_client>=5.1.0, <6.0
 matplotlib>=3.0.3, <4.0

tools/min_version.py

@@ -27,30 +27,22 @@
 # limitations under the License.
 
 """
-Black needs python 3.6+, but Kedro should work on 3.5 too,
-that's why we can't put ``black`` into test_requirements.txt and
-have to install it manually like that.
+Black and import-linter need python 3.6+, but Kedro should work on 3.5 too.
+That's why we run the relevant commands conditionally on CI/precommit.
 
 If python version is 3.5 - just exit with 0 status.
 """
-import platform
 import shlex
 import subprocess
 import sys
 
 if __name__ == "__main__":
     required_version = tuple(int(x) for x in sys.argv[1].strip().split("."))
-    install_cmd = shlex.split(sys.argv[2])
-    run_cmd = shlex.split(sys.argv[3])
-
-    current_version = tuple(map(int, platform.python_version_tuple()[:2]))
+    current_version = sys.version_info[:2]
 
     if current_version < required_version:
         print("Python version is too low, exiting")
         sys.exit(0)
 
-    try:
-        subprocess.run(run_cmd, check=True)
-    except (FileNotFoundError, subprocess.CalledProcessError):
-        subprocess.run(install_cmd, check=True)
-        subprocess.run(run_cmd, check=True)
+    run_cmd = shlex.split(sys.argv[2])
+    subprocess.run(run_cmd, check=True)