From d13d70fd56419b12786226af0067ef66a2904031 Mon Sep 17 00:00:00 2001
From: "James R. Barlow" <jim@purplerock.ca>
Date: Fri, 10 Apr 2020 01:27:46 -0700
Subject: [PATCH] Fix version checker failing for qpdf 10.0.0

Fixes #527
---
 src/ocrmypdf/exec/__init__.py |  3 ++-
 tests/test_validation.py      | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/ocrmypdf/exec/__init__.py b/src/ocrmypdf/exec/__init__.py
index 838697fc..1fb3b047 100644
--- a/src/ocrmypdf/exec/__init__.py
+++ b/src/ocrmypdf/exec/__init__.py
@@ -23,6 +23,7 @@ import re
 import shutil
 import sys
 from collections.abc import Mapping
+from distutils.version import LooseVersion
 from functools import lru_cache
 from subprocess import PIPE, STDOUT, CalledProcessError
 from subprocess import run as subprocess_run
@@ -270,7 +271,7 @@ def check_external_program(
             raise MissingDependencyError()
         return
 
-    if found_version < need_version:
+    if LooseVersion(found_version) < LooseVersion(need_version):
         _error_old_version(program, package, need_version, found_version, required_for)
         if not recommended:
             raise MissingDependencyError()
diff --git a/tests/test_validation.py b/tests/test_validation.py
index fb03de3b..9fc5fe39 100644
--- a/tests/test_validation.py
+++ b/tests/test_validation.py
@@ -176,3 +176,31 @@ def test_language_warning(caplog):
         vd.check_options_languages(opts)
         assert opts.language == ['eng']
         assert 'assuming --language' in caplog.text
+
+
+def test_version_comparison():
+    vd.check_external_program(
+        program="dummy_basic",
+        package="dummy",
+        version_checker=lambda: '9.0',
+        need_version='8.0.2',
+    )
+    vd.check_external_program(
+        program="dummy_doubledigit",
+        package="dummy",
+        version_checker=lambda: '10.0',
+        need_version='8.0.2',
+    )
+    vd.check_external_program(
+        program="tesseract",
+        package="tesseract",
+        version_checker=lambda: '4.0.0-beta.1',
+        need_version='4.0.0',
+    )
+    with pytest.raises(MissingDependencyError):
+        vd.check_external_program(
+            program="dummy_fails",
+            package="dummy",
+            version_checker=lambda: '1.0',
+            need_version='2.0',
+        )