Fix functional tests: Use --no-build-isolation to avoid setuptools dependency

Author: Ashutosh0x

tests/functional/test_index_strategy.py

@@ -8,34 +8,41 @@ def test_index_strategy_first_match_functional(
     Functional test for --index-strategy first-match.
     Index 1: data.index_url("simple") -> contains simple 1.0
     Index 2: data.index_url("yanked") -> contains simple 1.0, 2.0, 3.0
-    By default (best-match), pip should pick 3.0.
-    With --index-strategy first-match and Index 1 first, it should pick 1.0.
+
+    Note: We use --no-build-isolation to avoid needing setuptools from
+    the test indexes, since we're only testing index selection logic.
     """
-    # Verify best-match (default) picks 3.0
+    # Verify best-match (default) picks 2.0 (3.0 is yanked)
     result = script.pip(
         "install",
         "simple",
         "--dry-run",
+        "--no-build-isolation",
         "--index-url",
         data.index_url("simple"),
         "--extra-index-url",
         data.index_url("yanked"),
     )
-    assert "Would install simple-3.0" in result.stdout, f"Actual output: {result.stdout}"
+    assert "Would install simple-2.0" in result.stdout, (
+        f"Actual output: {result.stdout}"
+    )
 
     # Verify first-match picks 1.0 from the first index (index-url)
     result = script.pip(
         "install",
         "simple",
         "--dry-run",
+        "--no-build-isolation",
         "--index-strategy",
         "first-match",
         "--index-url",
         data.index_url("simple"),
         "--extra-index-url",
         data.index_url("yanked"),
     )
-    assert "Would install simple-1.0" in result.stdout, f"Actual output: {result.stdout}"
+    assert "Would install simple-1.0" in result.stdout, (
+        f"Actual output: {result.stdout}"
+    )
 
 
 def test_index_strategy_find_links_combo(
@@ -46,16 +53,22 @@ def test_index_strategy_find_links_combo(
     Find-links: data.find_links -> contains 3.0
     Index-url: data.index_url("simple") -> contains 1.0
     Even in first-match mode, find-links should be searched first and 3.0 picked.
+
+    Note: We use --no-build-isolation to avoid needing setuptools from
+    the test indexes, since we're only testing index selection logic.
     """
     result = script.pip(
         "install",
         "simple",
         "--dry-run",
+        "--no-build-isolation",
         "--index-strategy",
         "first-match",
         "--find-links",
         data.find_links,
         "--index-url",
         data.index_url("simple"),
     )
-    assert "Would install simple-3.0" in result.stdout, f"Actual output: {result.stdout}"
+    assert "Would install simple-3.0" in result.stdout, (
+        f"Actual output: {result.stdout}"
+    )

tests/unit/test_index_strategy.py

@@ -16,7 +16,8 @@ def test_index_strategy_best_match(data: TestData) -> None:
     assert "1.0" in version_strs
     assert "2.0" in version_strs
     assert "3.0" in version_strs
-    # We expect 4 candidates (1.0 from simple index, and 1.0, 2.0, 3.0 from yanked index)
+    # We expect 4 candidates:
+    # 1.0 from simple index, and 1.0, 2.0, 3.0 from yanked index
     assert len(version_strs) == 4