Added logic for creation of baseline images

SidharthBansal · SidharthBansal · commit c8857298039f · 2020-07-06T15:55:05.000+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 +504,44 @@ 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():
+    mplRepoPath = Path(mpl.__file__).parent
+    # Check that git is installed.
+    run_text_mode(shutil.which('git')) == None
+    # Check if current repository is a git repository
+    run_text_mode(['git', 'status'],
+                    cwd = mplRepoPath) == None
+    # Create virtual env in tmpdir.
+    if not (mplRepoPath / 'testenv').exists():
+        modify_existing_baseline_images()
+    else
+        # Clone mpl repo to tmpvenv and run pytests from new mpl repo created
+        run_text_mode(["git", "worktree", "add", "testenv"],
+                        cwd = mplRepoPath)
+        testenvPath = mplRepoPath / testenv
+        run_text_mode([sys.executable, "-mvenv", "venv"],
+                        cwd = testenvPath)
+        run_text_mode(["source", "venv/bin/activate"],
+                        cwd = testenvPath)
+        run_text_mode(["git", "checkout", "HEAD~"],
+                        cwd = testenvPath)
+        run_text_mode(["python", "-mpip", "install", "-e", mplRepoPath],
+                        cwd = testenvPath)
+        run_text_mode(["python", "-mpytest"],
+                        cwd = testenvPath)
+        # Copy result_images in the temporary directory and cache it
+        run_text_mode(shutil.copytree(testenvPath / "result_images",
+                                        mplRepoPath / ".pytest_cache"),
+                        cwd = mplRepoPath)
+
+ def modify_existing_baseline_images():
+     # TODO
+     return
+
+def run_text_mode(*args, **kwargs):
+    return subprocess.run(*args, **kwargs,
+                    stderr=subprocess.STDOUT,
+                    stdout = open(os.devnull, 'w'),
+                    universal_newlines=True)
