Added logic for creation of baseline images

SidharthBansal · SidharthBansal · commit c5b14869d46a · 2020-07-01T18:42:32.000+05:30
diff --git a/.gitignore b/.gitignore
@@ -104,3 +104,7 @@ lib/z.lib
 #########################
 lib/matplotlib/backends/web_backend/node_modules/
 lib/matplotlib/backends/web_backend/package-lock.json
+
+# Matplotlib tempenv #
+######################
+temp/testenv
diff --git a/lib/matplotlib/testing/decorators.py b/lib/matplotlib/testing/decorators.py
@@ -6,6 +6,7 @@
 from pathlib import Path
 import shutil
 import string
+import subprocess
 import sys
 import unittest
 import warnings
@@ -486,15 +487,14 @@ def _image_directories(func):
         try:
             import matplotlib_baseline_images
         except:
-            raise ImportError("Not able to import matplotlib_baseline_images")
+            generate_matplotlib_baseline_images_from_previous_commit()
         baseline_dir = (Path(matplotlib_baseline_images.__file__).parent /
                             module_path.stem)
     elif func.__module__.startswith("mpl_toolkits."):
         try:
             import mpl_toolkits_baseline_images
         except:
-            raise ImportError("Not able to import "
-                              "mpl_toolkits_baseline_images")
+            generate_matplotlib_baseline_images_from_previous_commit()
         baseline_dir = (Path(mpl_toolkits_baseline_images.__file__).parent /
                             module_path.stem)
     else:
@@ -504,3 +504,55 @@ def _image_directories(func):
     result_dir = Path().resolve() / "result_images" / module_path.stem
     result_dir.mkdir(parents=True, exist_ok=True)
     return baseline_dir, result_dir
+
+
+def generate_matplotlib_baseline_images_from_previous_commit():
+    # Check that git is installed.
+    subprocess.run(shutil.which('git'),
+                    stderr=subprocess.STDOUT,
+                    stdout = open(os.devnull, 'w'),
+                    universal_newlines=True) == None
+    # Check if current repository is a git repository
+    subprocess.run(['git', 'status'],
+                    cwd = Path(mpl.__file__).parent,
+                    stderr=subprocess.STDOUT,
+                    stdout = open(os.devnull, 'w'),
+                    universal_newlines=True) == None
+    # Create virtual env in tmpdir.
+    subprocess.run(["python", "-mvenv", "tmp/testenv"],
+                    cwd = "Path(mpl.__file__).parent",
+                    stderr=subprocess.STDOUT,
+                    stdout=subprocess.DEVNULL),
+                    universal_newlines=True)
+    # Clone mpl repo to tmpvenv and run pytests from new mpl repo created
+    subprocess.run(["git", "clone", cwd, "tmp/testenv"],
+                    cwd = Path(mpl.__file__).parent,
+                    stderr=subprocess.STDOUT,
+                    stdout=subprocess.DEVNULL,
+                    universal_newlines=True)
+    subprocess.run(["tmp/testenv/bin/python"],
+                    cwd = Path(mpl.__file__).parent,
+                    stderr=subprocess.STDOUT,
+                    stdout=subprocess.DEVNULL,
+                    universal_newlines=True)
+    subprocess.run(["git", "checkout", "HEAD~"],
+                    cwd = Path(mpl.__file__).parent,
+                    stderr=subprocess.STDOUT,
+                    stdout=subprocess.DEVNULL,
+                    universal_newlines=True)
+    subprocess.run(["python", "-mpip", "install", "-e", cwd],
+                    cwd = Path(mpl.__file__).parent,
+                    stderr=subprocess.STDOUT,
+                    stdout=subprocess.DEVNULL,
+                    universal_newlines=True)
+    subprocess.run(["python", "-mpytest"],
+                    cwd = Path(mpl.__file__).parent,
+                    stderr=subprocess.STDOUT,
+                    stdout=subprocess.DEVNULL,
+                    universal_newlines=True)
+    # Copy result_images in the temporary directory and cache it
+    subprocess.run(shutil.copytree("result_images", "tempenv/.pytest_cache"),
+                    cwd = Path(mpl.__file__).parent,
+                    stderr=subprocess.STDOUT,
+                    stdout=subprocess.DEVNUL,
+                    universal_newlines=True)
