Replace cryptic test error messages with more informative ones

tests/plugins/gs_raster_failure.py

@@ -13,7 +13,7 @@ from ocrmypdf.builtin_plugins import ghostscript
 
 def raise_gs_fail(*args, **kwargs):
     raise CalledProcessError(
-        1, 'gs', output=b"", stderr=b"ERROR: Ghost story archive not found"
+        1, 'gs', output=b"", stderr=b"TEST ERROR: gs_raster_failure.py"
     )
 
 

tests/plugins/gs_render_failure.py

@@ -12,7 +12,7 @@ from ocrmypdf.builtin_plugins import ghostscript
 
 def raise_gs_fail(*args, **kwargs):
     raise CalledProcessError(
-        1, 'gs', output=b"", stderr=b"ERROR: Casper is not a friendly ghost"
+        1, 'gs', output=b"", stderr=b"TEST ERROR: gs_render_failure.py"
     )
 
 

tests/test_ghostscript.py

@@ -84,7 +84,7 @@ def test_gs_render_failure(resources, outpdf):
         '--plugin',
         'tests/plugins/gs_render_failure.py',
     )
-    assert 'Casper is not a friendly ghost' in p.stderr
+    assert 'TEST ERROR: gs_render_failure.py' in p.stderr
     assert p.returncode == ExitCode.child_process_error
 
 
@@ -97,7 +97,7 @@ def test_gs_raster_failure(resources, outpdf):
         '--plugin',
         'tests/plugins/gs_raster_failure.py',
     )
-    assert 'Ghost story archive not found' in p.stderr
+    assert 'TEST ERROR: gs_raster_failure.py' in p.stderr
     assert p.returncode == ExitCode.child_process_error