[python] PY-83776: Python list can't be sorted due to "Comparison method violates its general contract!".

`com.intellij.python.community.services.shared.PythonInfoWithUiComparator` sorts by `PythonInfoComparator` and then by `UiComparator`.

It used to multiply first result to `10` trying to shift it one digit left, but `compare` contract doesn't guarantee anything except the sign. It could be `-233` for certain tool names (i.e: different lengths, different characters with a huge distance between their codes).

We now only check contract


Merge-request: IJ-MR-186470
Merged-by: Ilya Kazakevich <ilya.kazakevich@jetbrains.com>

GitOrigin-RevId: 89e9b3de2bd0e4b46d1c213f3b262dd698462275

python/services/shared/src/com/intellij/python/community/services/shared/comparators.kt

@@ -32,7 +32,11 @@ class PythonInfoWithUiComparator<T> : Comparator<T> where T : PythonInfoHolder,
     if (logger.isTraceEnabled) {
       logger.trace("full ${o1.string()} vs ${o2.string()}")
     }
-    return PythonInfoComparator.compare(o1, o2) * 10 + UiComparator.compare(o1, o2)
+    val infoResult = PythonInfoComparator.compare(o1, o2)
+    if (infoResult != 0) {
+      return infoResult
+    }
+    return UiComparator.compare(o1, o2)
   }
 }
 

python/services/shared/tests/com/intellij/python/junit5Tests/unit/comparators/ComparatorsTest.kt

@@ -9,6 +9,7 @@ import com.jetbrains.python.PythonInfo
 import com.jetbrains.python.psi.LanguageLevel
 import org.hamcrest.MatcherAssert
 import org.hamcrest.Matchers
+import org.junit.jupiter.api.Assertions
 import org.junit.jupiter.api.Test
 import java.util.*
 
@@ -41,9 +42,43 @@ class ComparatorsTest {
       MockInfo(PythonInfo(LanguageLevel.PYTHON27))
     ))
   }
+
+  /**
+   * Check [Comparator.compare] contract for [PythonInfoWithUiComparator]
+   */
+  @Test
+  fun testCompareContract() {
+    val longName = " ".repeat(100)
+    val data = mutableListOf<MockInfo>()
+    for (lang in LanguageLevel.entries) {
+      for (free in arrayOf(true, false)) {
+        for (title in arrayOf(null, "uv", "homebrew", " ", "ÿ", longName)) {
+          val ui = if (title == null) null else PyToolUIInfo(title)
+          data.add(MockInfo(PythonInfo(lang, free), ui))
+        }
+      }
+    }
+
+    for (x in data) {
+      Assertions.assertEquals(0, x.compareTo(x), "Reflexivity broken for $x")
+      for (y in data) {
+        Assertions.assertEquals(-(y.compareTo(x)), x.compareTo(y), "Antisymmetry broken for $x, $y")
+        for (z in data) {
+          if (x > y && y > z) {
+            Assertions.assertTrue(x > z, "Transitivity broken for $x, $y, $z")
+          }
+        }
+      }
+    }
+  }
 }
 
 private data class MockInfo(
   override val pythonInfo: PythonInfo,
   override val ui: PyToolUIInfo? = null,
-) : PythonInfoHolder, UiHolder
+) : PythonInfoHolder, UiHolder, Comparable<MockInfo> {
+
+  override fun compareTo(other: MockInfo): Int = COMPARATOR.compare(this, other)
+}
+
+private val COMPARATOR = PythonInfoWithUiComparator<MockInfo>()