Add the import linter with rules to cover our core modules (#177)

.pre-commit-config.yaml

@@ -72,9 +72,14 @@ repos:
         name: "Black"
         language: system
         pass_filenames: false
-        entry: python -m tools.black_runner kedro extras features tests
+        entry: python -m tools.min_version 3.6 "pip install black" "black kedro extras features tests"
     -   id: legal
         name: "Licence check"
         language: system
         pass_filenames: false
         entry: make legal
+    -   id: imports
+        name: "Import Linter"
+        language: system
+        pass_filenames: false
+        entry: python -m tools.min_version 3.6 "pip install import-linter" lint-imports

setup.cfg

@@ -9,3 +9,46 @@ addopts=--cov-report xml:coverage.xml
         --cov tests
         --no-cov-on-fail
         -ra
+
+[importlinter]
+root_package = kedro
+
+[importlinter:contract:1]
+name = Contrib > CLI > Context > Library, Runner > IO & Pipeline
+type = layers
+containers = kedro
+layers =
+    contrib
+    cli
+    context
+    runner
+    io
+    pipeline
+    config
+
+[importlinter:contract:2]
+name = Pipeline and IO are independent
+type = independence
+modules =
+    kedro.pipeline
+    kedro.io
+
+[importlinter:contract:3]
+name = Config can't import Runner et al
+type = forbidden
+source_modules =
+    kedro.config
+forbidden_modules =
+    kedro.runner
+    kedro.io
+    kedro.pipeline
+
+[importlinter:contract:4]
+name = Runner et al can't import Config
+type = forbidden
+source_modules =
+    kedro.runner
+    kedro.io
+    kedro.pipeline
+forbidden_modules =
+    kedro.config

tools/black_runner.py → tools/min_version.py

@@ -34,19 +34,23 @@
 If python version is 3.5 - just exit with 0 status.
 """
 import platform
+import shlex
 import subprocess
 import sys
 
-VERSION = tuple(map(int, platform.python_version_tuple()[:2]))
+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])
 
-if VERSION < (3, 6):
-    print("Python version is too low, exiting")
-    sys.exit(0)
+    current_version = tuple(map(int, platform.python_version_tuple()[:2]))
 
-try:
-    import black  # noqa: F401 pylint: disable=unused-import
-except ImportError:
-    subprocess.run(["pip", "install", "black"], check=True)
+    if current_version < required_version:
+        print("Python version is too low, exiting")
+        sys.exit(0)
 
-
-subprocess.run(["black"] + sys.argv[1:], check=True)
+    try:
+        subprocess.run(run_cmd, check=True)
+    except FileNotFoundError:
+        subprocess.run(install_cmd, check=True)
+        subprocess.run(run_cmd, check=True)