Unit test for https://github.com/apache/lucene/pull/711

lucene/core/src/java/org/apache/lucene/search/MaxScoreSumPropagator.java

@@ -127,8 +127,15 @@ void setMinCompetitiveScore(float minScore) throws IOException {
       scorers[i].setMinCompetitiveScore(minCompetitiveScore);
     }
   }
-
-  /** Return the minimum score that a Scorer must produce in order for a hit to be competitive. */
+
+  /**
+   * Return the minimum score that a Scorer must produce in order for a hit to be competitive.
+   * 
+   * The way that boolean queries combine scores of their sub clauses together is by summing up the
+   * float scores into a double and finally casting back that double back to a float. This method undoes
+   * this operation by taking the float score sum and subtracting the sum of other scores as a double as
+   * a first approximation of the minimum score that this clause must have.
+   */
   private float getMinCompetitiveScore(float minScoreSum, double sumOfOtherMaxScores) {
     assert numClauses > 0;
 
@@ -146,7 +153,9 @@ private float getMinCompetitiveScore(float minScoreSum, double sumOfOtherMaxScor
       //  - one because of the error introduced by sumUpperBound
       if (iter > 2) {
         throw new IllegalStateException(
-            "Could not compute a minimum score for minScoreSum="
+            "Could not compute a minimum score for minScore=" + 
+                + minScore
+                + ", minScoreSum="
                 + minScoreSum
                 + ", sumOfOtherMaxScores="
                 + sumOfOtherMaxScores

lucene/core/src/test/org/apache/lucene/search/TestMaxScoreSumPropagator.java

@@ -229,4 +229,27 @@ private void assertMinCompetitiveScore(
           (float) scoreSum <= minCompetitiveScore);
     }
   }
+
+  /*
+    In https://issues.apache.org/jira/browse/LUCENE-10428 we have observed an issue in production
+    causing an infinite loop in MaxScoreSumPropagator.getMinCompetitiveScore. This is likely
+    caused by calling code that is breaking the assumptions made by MaxScoreSumPropagator, 
+    e.g. a query that produces negative or NaN scores. This test reproduces that scenario,
+    and asserts that getMinCompetitiveScore aborts after more than 2 iterations.
+
+    See https://github.com/apache/lucene/pull/711.
+  */
+  public void testMinCompetitiveScoreIllegalState() throws Exception {   
+    List<FakeScorer> scorers = new ArrayList<>();
+    scorers.add(new FakeScorer(-0.16903716f));
+    scorers.add(new FakeScorer(0.62573546f));
+    scorers.add(new FakeScorer(-0.64014715f));
+    float minScoreSum = 0.31314075f;
+    MaxScoreSumPropagator p = new MaxScoreSumPropagator(scorers);
+    Throwable exception = assertThrows(IllegalStateException.class, () -> p.setMinCompetitiveScore(minScoreSum));
+    assertEquals(
+      "Could not compute a minimum score for minScore=1.1223251, minScoreSum=0.31314072, sumOfOtherMaxScores=-0.8091843128204346, numClauses=3", 
+      exception.getMessage()
+    );
+  }
 }