Add regression test for large attr issue (#46)

The test processes an SVG file of ~36MB with about 500k points per
layer, so it's a bit slow.

gerbolyze/tests/test_regression.py

@@ -0,0 +1,75 @@
+#s -*- coding: utf-8 -*-
+#
+# Copyright 2022 Jan Götte <code@jaseg.de>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import sys
+import math
+import subprocess
+import tempfile
+from pathlib import Path
+from xml.etree import ElementTree
+
+import gerbonara
+import pytest
+
+from .test_integration import run_command
+
+
+
+def test_template_round_trip():
+    r = 50 # mm
+    n_points = 500000
+
+    with tempfile.NamedTemporaryFile(suffix='.svg') as out_svg,\
+            tempfile.NamedTemporaryFile(suffix='.svg') as proc_svg,\
+            tempfile.TemporaryDirectory() as out_dir:
+            run_command('python3', 'gerbolyze', 'empty-template', '--force', '--size', f'{2*(r)}x{2*(r)}mm', out_svg.name)
+
+            ElementTree.register_namespace('', 'http://www.w3.org/2000/svg')
+            ElementTree.register_namespace('svg', 'http://www.w3.org/2000/svg')
+            et = ElementTree.parse(out_svg)
+            for layer in [
+                    et.find(".//{http://www.w3.org/2000/svg}g[@id='g-top-copper']"),
+                    et.find(".//{http://www.w3.org/2000/svg}g[@id='g-bottom-copper']")]:
+                poly = ElementTree.SubElement(layer, '{http://www.w3.org/2000/svg}polygon')
+                # Generate n_points points on a circle
+                poly.set('points', ' '.join([f'{r + r*math.sin(t)}, {r + r*math.cos(t)}'
+                                             for t in (i/n_points * 2*math.pi for i in range(n_points))]))
+
+            et.write(proc_svg)
+            proc_svg.flush()
+
+            run_command('python3', 'gerbolyze', 'convert', proc_svg.name, out_dir)
+            out_dir = Path(out_dir)
+
+            excellon_files = [f.stat().st_size for f in out_dir.glob('*.drl')]
+            print('Excellon file sizes:', excellon_files)
+
+            gerber_files = {f: f.stat().st_size for f in out_dir.glob('*.gbr')}
+            print('Gerber file sizes:', gerber_files)
+
+            assert len(excellon_files) == 2
+            assert all(20 < x < 100 for x in excellon_files)
+
+            for f, size in gerber_files.items():
+                _name, _, layer = f.stem.rpartition('-')
+                if layer in ('F.Cu', 'B.Cu'):
+                    # These layers should contain a very large G36 polygon
+                    assert 10e6 < size < 100e6
+                else:
+                    # These layers should not contain anything
+                    assert 20 < size < 1000
+