Use a better way to construct file names in test_commands

There is no need for the strings to be real file paths and using
string manipulation to build the file names is error prone. Define
simple helpers that construct the file names as needed. This makes the
tests intent and implementation easier to understand.

tests/test_commands.py

@@ -1,8 +1,8 @@
+import dataclasses
 import os
 
 import pytest
 
-from tests import helpers
 from twine import commands
 from twine import exceptions
 
@@ -52,41 +52,69 @@ def test_find_dists_handles_real_files():
     assert expected == files
 
 
+class Signed(str):
+
+    @property
+    def signature(self):
+        return f"{self}.asc"
+
+    def attestation(self, what):
+        return f"{self}.{what}.attestation"
+
+
+@dataclasses.dataclass
+class Distribution:
+    name: str
+    version: str
+
+    @property
+    def sdist(self):
+        return Signed(f"dist/{self.name}-{self.version}.tar.gz")
+
+    @property
+    def wheel(self):
+        return Signed(f"dist/{self.name}-{self.version}-py2.py3-none-any.whl")
+
+
 def test_split_inputs():
     """Split inputs into dists, signatures, and attestations."""
+    a = Distribution("twine", "1.5.0")
+    b = Distribution("twine", "1.6.5")
+
     inputs = [
-        helpers.WHEEL_FIXTURE,
-        helpers.WHEEL_FIXTURE + ".asc",
-        helpers.WHEEL_FIXTURE + ".build.attestation",
-        helpers.WHEEL_FIXTURE + ".publish.attestation",
-        helpers.SDIST_FIXTURE,
-        helpers.SDIST_FIXTURE + ".asc",
-        helpers.NEW_WHEEL_FIXTURE,
-        helpers.NEW_WHEEL_FIXTURE + ".frob.attestation",
-        helpers.NEW_SDIST_FIXTURE,
+        a.wheel,
+        a.wheel.signature,
+        a.wheel.attestation("build"),
+        a.wheel.attestation("build.publish"),
+        a.sdist,
+        a.sdist.signature,
+        b.wheel,
+        b.wheel.attestation("frob"),
+        b.sdist,
     ]
 
     inputs = commands._split_inputs(inputs)
 
     assert inputs.dists == [
-        helpers.WHEEL_FIXTURE,
-        helpers.SDIST_FIXTURE,
-        helpers.NEW_WHEEL_FIXTURE,
-        helpers.NEW_SDIST_FIXTURE,
+        a.wheel,
+        a.sdist,
+        b.wheel,
+        b.sdist,
     ]
 
-    expected_signatures = {
-        os.path.basename(dist) + ".asc": dist + ".asc"
-        for dist in [helpers.WHEEL_FIXTURE, helpers.SDIST_FIXTURE]
+    assert inputs.signatures == {
+        "twine-1.5.0-py2.py3-none-any.whl.asc": a.wheel.signature,
+        "twine-1.5.0.tar.gz.asc": a.sdist.signature,
     }
-    assert inputs.signatures == expected_signatures
 
     assert inputs.attestations_by_dist == {
-        helpers.WHEEL_FIXTURE: [
-            helpers.WHEEL_FIXTURE + ".build.attestation",
-            helpers.WHEEL_FIXTURE + ".publish.attestation",
+        a.wheel: [
+            a.wheel.attestation("build"),
+            a.wheel.attestation("build.publish"),
+        ],
+        a.sdist: [],
+        b.wheel: [
+            b.wheel.attestation("frob"),
         ],
-        helpers.SDIST_FIXTURE: [],
-        helpers.NEW_WHEEL_FIXTURE: [helpers.NEW_WHEEL_FIXTURE + ".frob.attestation"],
-        helpers.NEW_SDIST_FIXTURE: [],
+        b.sdist: [],
     }