Change most tests to use ocrmypdf API instead of subprocess

The main benefit of this is code coverage gains can actually follow it.
Also removes most ugly os.environ hacks.

src/ocrmypdf/exec/__init__.py

@@ -28,7 +28,7 @@ from collections.abc import Mapping
 log = logging.Logger(__name__)
 
 
-def get_version(program, *, version_arg='--version', regex=r'(\d+(\.\d+)*)'):
+def get_version(program, *, version_arg='--version', regex=r'(\d+(\.\d+)*)', env=None):
     "Get the version of the specified program"
     args_prog = [program, version_arg]
     try:
@@ -39,6 +39,7 @@ def get_version(program, *, version_arg='--version', regex=r'(\d+(\.\d+)*)'):
             stdout=PIPE,
             stderr=STDOUT,
             check=True,
+            env=env,
         )
         output = proc.stdout
     except FileNotFoundError as e:

src/ocrmypdf/exec/tesseract.py

@@ -60,18 +60,16 @@ HOCR_TEMPLATE = """<?xml version="1.0" encoding="UTF-8"?>
 """
 
 
-@lru_cache(maxsize=1)
-def version():
-    return get_version('tesseract', regex=r'tesseract\s(.+)')
+def version(tesseract_env=None):
+    return get_version('tesseract', regex=r'tesseract\s(.+)', env=tesseract_env)
 
 
-def v4():
+def v4(tesseract_env=None):
     "Is this Tesseract v4.0?"
-    return version() >= '4'
+    return version(tesseract_env) >= '4'
 
 
-@lru_cache(maxsize=1)
-def has_textonly_pdf():
+def has_textonly_pdf(tesseract_env=None):
     """Does Tesseract have textonly_pdf capability?
 
     Available in v4.00.00alpha since January 2017. Best to
@@ -80,7 +78,15 @@ def has_textonly_pdf():
     args_tess = ['tesseract', '--print-parameters', 'pdf']
     params = ''
     try:
-        params = check_output(args_tess, universal_newlines=True, stderr=STDOUT)
+        proc = run(
+            args_tess,
+            check=True,
+            universal_newlines=True,
+            stdout=PIPE,
+            stderr=STDOUT,
+            env=tesseract_env,
+        )
+        params = proc.stdout
     except CalledProcessError as e:
         print("Could not --print-parameters from tesseract", file=sys.stderr)
         raise MissingDependencyError from e
@@ -89,8 +95,7 @@ def has_textonly_pdf():
     return False
 
 
-@lru_cache(maxsize=1)
-def languages():
+def languages(tesseract_env=None):
     def lang_error(output):
         msg = dedent(
             """Tesseract failed to report available languages.
@@ -104,7 +109,12 @@ def languages():
     args_tess = ['tesseract', '--list-langs']
     try:
         proc = run(
-            args_tess, universal_newlines=True, stdout=PIPE, stderr=STDOUT, check=True
+            args_tess,
+            universal_newlines=True,
+            stdout=PIPE,
+            stderr=STDOUT,
+            check=True,
+            env=tesseract_env,
         )
         output = proc.stdout
     except CalledProcessError as e:
@@ -127,7 +137,7 @@ def tess_base_args(langs, engine_mode):
     return args
 
 
-def get_orientation(input_file, engine_mode, timeout: float, log):
+def get_orientation(input_file, engine_mode, timeout: float, log, tesseract_env=None):
     args_tesseract = tess_base_args(['osd'], engine_mode) + [
         '--psm',
         '0',
@@ -136,7 +146,15 @@ def get_orientation(input_file, engine_mode, timeout: float, log):
     ]
 
     try:
-        stdout = check_output(args_tesseract, stderr=STDOUT, timeout=timeout)
+        p = run(
+            args_tesseract,
+            stdout=PIPE,
+            stderr=STDOUT,
+            timeout=timeout,
+            check=True,
+            env=tesseract_env,
+        )
+        stdout = p.stdout
     except TimeoutExpired:
         return OrientationConfidence(angle=0, confidence=0.0)
     except CalledProcessError as e:
@@ -235,6 +253,7 @@ def generate_hocr(
     pagesegmode: int,
     user_words,
     user_patterns,
+    tesseract_env,
     log,
 ):
 
@@ -258,7 +277,15 @@ def generate_hocr(
     args_tesseract.extend([input_file, prefix, 'hocr', 'txt'] + tessconfig)
     try:
         log.debug(args_tesseract)
-        stdout = check_output(args_tesseract, stderr=STDOUT, timeout=timeout)
+        p = run(
+            args_tesseract,
+            stdout=PIPE,
+            stderr=STDOUT,
+            timeout=timeout,
+            check=True,
+            env=tesseract_env,
+        )
+        stdout = p.stdout
     except TimeoutExpired:
         # Generate a HOCR file with no recognized text if tesseract times out
         # Temporary workaround to hocrTransform not being able to function if
@@ -310,9 +337,10 @@ def generate_pdf(
     pagesegmode: int,
     user_words,
     user_patterns,
+    tesseract_env,
     log,
 ):
-    '''Use Tesseract to render a PDF.
+    """Use Tesseract to render a PDF.
 
     input_image -- image to analyze
     skip_pdf -- if we time out, use this file as output
@@ -324,14 +352,14 @@ def generate_pdf(
     tessconfig -- tesseract configuration
     timeout -- timeout (seconds)
     log -- logger object
-    '''
+    """
 
     args_tesseract = tess_base_args(language, engine_mode)
 
     if pagesegmode is not None:
         args_tesseract.extend(['--psm', str(pagesegmode)])
 
-    if text_only and has_textonly_pdf():
+    if text_only and has_textonly_pdf(tesseract_env):
         args_tesseract.extend(['-c', 'textonly_pdf=1'])
 
     if user_words:
@@ -348,7 +376,15 @@ def generate_pdf(
     args_tesseract.extend([input_image, prefix, 'pdf', 'txt'] + tessconfig)
     try:
         log.debug(args_tesseract)
-        stdout = check_output(args_tesseract, stderr=STDOUT, timeout=timeout)
+        p = run(
+            args_tesseract,
+            stdout=PIPE,
+            stderr=STDOUT,
+            timeout=timeout,
+            check=True,
+            env=tesseract_env,
+        )
+        stdout = p.stdout
         if os.path.exists(prefix + '.txt'):
             shutil.move(prefix + '.txt', output_text)
     except TimeoutExpired: