From d1852a5f8e2cd33602d670cf602593e664c7a2a7 Mon Sep 17 00:00:00 2001
From: Chris Sewell <chrisj_sewell@hotmail.com>
Date: Tue, 25 Apr 2023 19:42:26 +0200
Subject: [PATCH] =?UTF-8?q?=F0=9F=94=A7=20Add=20tox=20env=20for=20fuzz=20t?=
 =?UTF-8?q?estcase=20run=20(#263)?=
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To reproduce failing test cases reported by Google's OSS-Fuzz runs
---
 .github/workflows/fuzz.yml         |  2 ++
 docs/conf.py                       |  2 +-
 scripts/build_fuzzers.py           | 42 ++++++++++++++++++++++++++++++
 profiler.py => scripts/profiler.py |  0
 tox.ini                            |  9 ++++++-
 5 files changed, 53 insertions(+), 2 deletions(-)
 create mode 100644 scripts/build_fuzzers.py
 rename profiler.py => scripts/profiler.py (100%)

diff --git a/.github/workflows/fuzz.yml b/.github/workflows/fuzz.yml
index 7df6dc6b..a74869a5 100644
--- a/.github/workflows/fuzz.yml
+++ b/.github/workflows/fuzz.yml
@@ -6,9 +6,11 @@ name: fuzzing
 # to guard against code introducing crashes in the Markdown parsing,
 # which should in principle always run against any text input.
 # See: https://google.github.io/oss-fuzz/getting-started/continuous-integration/#how-it-works
+# Note, to reproduce a crash locally, copy to `testcase` file` and run: `tox -e fuzz`
 
 on:
   pull_request:
+    paths-ignore: ['docs/**', 'tests/**']
 
 jobs:
   Fuzzing:
diff --git a/docs/conf.py b/docs/conf.py
index 786eff04..52deea47 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -102,7 +102,7 @@ def run_apidoc(app):
     this_folder = os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
     api_folder = os.path.join(this_folder, "api")
     module_path = os.path.normpath(os.path.join(this_folder, "../"))
-    ignore_paths = ["../profiler.py", "../conftest.py", "../tests", "../benchmarking"]
+    ignore_paths = ["../scripts", "../conftest.py", "../tests", "../benchmarking"]
     ignore_paths = [
         os.path.normpath(os.path.join(this_folder, p)) for p in ignore_paths
     ]
diff --git a/scripts/build_fuzzers.py b/scripts/build_fuzzers.py
new file mode 100644
index 00000000..3dce8ddf
--- /dev/null
+++ b/scripts/build_fuzzers.py
@@ -0,0 +1,42 @@
+"""Build fuzzers idempotently in a given folder."""
+import argparse
+from pathlib import Path
+import subprocess
+
+
+def main():
+    """Build fuzzers idempotently in a given folder."""
+    parser = argparse.ArgumentParser()
+    parser.add_argument("folder")
+    args = parser.parse_args()
+    folder = Path(args.folder)
+    if not folder.exists():
+        print(f"Cloning google/oss-fuzz into: {folder}")
+        folder.mkdir(parents=True)
+        subprocess.check_call(
+            [
+                "git",
+                "clone",
+                "--single-branch",
+                "https://github.com/google/oss-fuzz",
+                str(folder),
+            ]
+        )
+    else:
+        print(f"Using google/oss-fuzz in: {folder}")
+    if not (folder / "build").exists():
+        print(f"Building fuzzers in: {folder / 'build'}")
+        subprocess.check_call(
+            [
+                "python",
+                str(folder / "infra" / "helper.py"),
+                "build_fuzzers",
+                "markdown-it-py",
+            ]
+        )
+    else:
+        print(f"Using existing fuzzers in: {folder / 'build'}")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/profiler.py b/scripts/profiler.py
similarity index 100%
rename from profiler.py
rename to scripts/profiler.py
diff --git a/tox.ini b/tox.ini
index 85a7179b..bf0c8367 100644
--- a/tox.ini
+++ b/tox.ini
@@ -55,11 +55,18 @@ allowlist_externals =
     dot
 commands =
     mkdir -p "{toxworkdir}/prof"
-    python -m cProfile -o "{toxworkdir}/prof/output.pstats" profiler.py
+    python -m cProfile -o "{toxworkdir}/prof/output.pstats" scripts/profiler.py
     gprof2dot -f pstats -o "{toxworkdir}/prof/output.dot" "{toxworkdir}/prof/output.pstats"
     dot -Tsvg -o "{toxworkdir}/prof/output.svg" "{toxworkdir}/prof/output.dot"
     python -c 'import pathlib; print("profiler svg output under file://\{0\}".format(pathlib.Path(r"{toxworkdir}") / "prof" / "output.svg"))'
 
+[testenv:fuzz]
+description = run fuzzer on testcase file
+; See: https://google.github.io/oss-fuzz/
+deps = atheris
+commands_pre = python scripts/build_fuzzers.py {envdir}/oss-fuzz
+commands = python {envdir}/oss-fuzz/infra/helper.py reproduce markdown-it-py fuzz_markdown {posargs:testcase}
+
 [flake8]
 max-line-length = 100
 extend-ignore = E203