Index error empty multilinestring (#949)

* add test cases for empty multilinestring.

* add tests for "_is_coordinates_empty"

* whitespace

* don't use pathlib so py2.7 tests pass

* try using Popen / communicate for py2.7 support

* remove print call

* account for python2/3 semantics

tests/test_shape.py

@@ -1,6 +1,7 @@
 import pytest
 
-from shapely.geometry import shape, Polygon
+from shapely.geometry import shape, Polygon, MultiLineString
+from shapely.geometry.geo import _is_coordinates_empty
 
 
 @pytest.mark.parametrize(
@@ -28,3 +29,23 @@ def test_polygon_not_empty_np_array():
     geom = {"type": "Polygon", "coordinates": np.array([[[5, 10], [10, 10], [10, 5]]])}
     obj = shape(geom)
     assert obj == Polygon([(5, 10), (10, 10), (10, 5)])
+
+
+@pytest.mark.parametrize("geom", [
+    {'type': "MultiLineString", "coordinates": []},
+    {'type': 'MultiLineString', 'coordinates': [[]]},
+    {'type': 'MultiLineString', 'coordinates': None}
+])
+def test_multilinestring_empty(geom):
+    assert shape(geom) == MultiLineString()
+
+
+@pytest.mark.parametrize("coords", [
+    [],
+    [[]],
+    [[], []],
+    None,
+    [[[]]]
+])
+def test_is_coordinates_empty(coords):
+    assert _is_coordinates_empty(coords)

tests/test_strtree.py

@@ -1,8 +1,8 @@
 import gc
+import os
 import pickle
 import subprocess
 import sys
-from pathlib import Path
 
 from shapely.strtree import STRtree
 from shapely.geometry import Point, Polygon
@@ -92,10 +92,11 @@ def test_pickle_persistence():
     """
     tree = STRtree([Point(i, i).buffer(0.1) for i in range(3)])
     pickled_strtree = pickle.dumps(tree)
-    print("pickled strtree:", repr(pickled_strtree))
-    unpickle_script_file_path = Path(__file__).parent / "unpickle-strtree.py"
-    subprocess.run(
+    unpickle_script_file_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), "unpickle-strtree.py")
+    proc = subprocess.Popen(
         [sys.executable, str(unpickle_script_file_path)],
-        input=pickled_strtree,
-        check=True
+        stdin=subprocess.PIPE,
     )
+    proc.communicate(input=pickled_strtree)
+    proc.wait()
+    assert proc.returncode == 0

tests/unpickle-strtree.py

@@ -10,7 +10,12 @@
 
 
 if __name__ == "__main__":
-    pickled_strtree = sys.stdin.buffer.read()
+    try:
+        pickled_strtree = sys.stdin.buffer.read()
+    except AttributeError:
+        # Python 2.7
+        pickled_strtree = sys.stdin.read()
+
     print("received pickled strtree:", repr(pickled_strtree))
     strtree = pickle.loads(pickled_strtree)
     # Exercise API.