Whitespace missing after URL in PEP508 string for URL Dependency

poetry/core/packages/dependency.py

@@ -228,7 +228,7 @@ def to_pep_508(self, with_extras=True):  # type: (bool) -> str
             )
 
         if markers:
-            if self.is_vcs():
+            if self.is_vcs() or self.is_url():
                 requirement += " "
 
             if len(markers) > 1:

tests/packages/test_url_dependency.py

@@ -0,0 +1,23 @@
+from poetry.core.packages import URLDependency
+from poetry.core.version.markers import SingleMarker
+
+
+def test_to_pep_508():
+    dependency = URLDependency(
+        "pytorch",
+        "https://download.pytorch.org/whl/cpu/torch-1.5.1%2Bcpu-cp38-cp38-linux_x86_64.whl",
+    )
+
+    expected = "pytorch @ https://download.pytorch.org/whl/cpu/torch-1.5.1%2Bcpu-cp38-cp38-linux_x86_64.whl"
+    assert expected == dependency.to_pep_508()
+
+
+def test_to_pep_508_with_marker():
+    dependency = URLDependency(
+        "pytorch",
+        "https://download.pytorch.org/whl/cpu/torch-1.5.1%2Bcpu-cp38-cp38-linux_x86_64.whl",
+    )
+    dependency.marker = SingleMarker("sys.platform", "linux")
+
+    expected = 'pytorch @ https://download.pytorch.org/whl/cpu/torch-1.5.1%2Bcpu-cp38-cp38-linux_x86_64.whl ; sys_platform == "linux"'
+    assert expected == dependency.to_pep_508()