1 files changed, 78 insertions, 0 deletions
diff --git a/container-search/src/test/java/com/yahoo/search/ranking/RangeAdjusterTest.java b/container-search/src/test/java/com/yahoo/search/ranking/RangeAdjusterTest.java
new file mode 100644
index 00000000000..af495d829b6
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+++ b/container-search/src/test/java/com/yahoo/search/ranking/RangeAdjusterTest.java
@@ -0,0 +1,78 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.ranking;
+
+import com.google.common.collect.RangeMap;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class RangeAdjusterTest {
+    static void rerank(RangeAdjuster adjuster, double before, double after) {
+        adjuster.withInitialScore(before);
+        adjuster.withFinalScore(after);
+    }
+    static double adjust(RangeAdjuster adjuster, double score) {
+        return score * adjuster.scale() + adjuster.bias();
+    }
+    @Test void noScoresNoNeed() {
+        var adjuster = new RangeAdjuster();
+        assertFalse(adjuster.rescaleNeeded());
+    }
+    @Test void increasingScoresNoNeed() {
+        var adjuster = new RangeAdjuster();
+        rerank(adjuster, 1.0, 2.0);
+        rerank(adjuster, 3.0, 4.0);
+        rerank(adjuster, 2.0, 3.0);
+        assertFalse(adjuster.rescaleNeeded());
+    }
+    @Test void singleScoreAdjuster() {
+        var adjuster = new RangeAdjuster();
+        rerank(adjuster, 10.0, 5.0);
+        assertEquals(adjuster.scale(), 1.0);
+        assertEquals(adjuster.bias(), -5.0);
+        assertEquals(adjust(adjuster, 10.0), 5.0);
+        assertEquals(adjust(adjuster, 7.0), 2.0);
+    }
+    @Test void movingAdjuster() {
+        var adjuster = new RangeAdjuster();
+        rerank(adjuster, -10.0, -15.0);
+        rerank(adjuster, -11.0, -16.0);
+        rerank(adjuster, -12.0, -17.0);
+        assertEquals(adjuster.scale(), 1.0);
+        assertEquals(adjuster.bias(), -5.0);
+        assertEquals(adjust(adjuster, -10.0), -15.0);
+        assertEquals(adjust(adjuster, -15.0), -20.0);
+    }
+    @Test void compactingAdjuster() {
+        var adjuster = new RangeAdjuster();
+        rerank(adjuster, 100.0, 10.0);
+        rerank(adjuster, 200.0, 20.0);
+        rerank(adjuster, 300.0, 30.0);
+        assertEquals(adjuster.scale(), 0.1);
+        assertEquals(adjuster.bias(), 0.0);
+        assertEquals(adjust(adjuster, 100.0), 10.0);
+        assertEquals(adjust(adjuster, 50.0), 5.0);
+    }
+    @Test void expandingAdjuster() {
+        var adjuster = new RangeAdjuster();
+        rerank(adjuster, -10.0, -100.0);
+        rerank(adjuster, -20.0, -200.0);
+        rerank(adjuster, -30.0, -300.0);
+        assertEquals(adjuster.scale(), 10.0);
+        assertEquals(adjuster.bias(), 0.0);
+        assertEquals(adjust(adjuster, -10.0), -100.0);
+        assertEquals(adjust(adjuster, -40.0), -400.0);
+    }
+    // this test represents the normal re-scaling case.
+    @Test void compactingAndMovingAdjuster() {
+        var adjuster = new RangeAdjuster();
+        rerank(adjuster, 1000.0, 1.0);
+        rerank(adjuster, 800.0, 0.8);
+        rerank(adjuster, 500.0, 0.5);
+        assertEquals(adjuster.scale(), 1.0/500.0);
+        assertEquals(adjuster.bias(), -0.5);
+        assertEquals(adjust(adjuster, 500.0), 0.5);
+        assertEquals(adjust(adjuster, 250.0), 0.0);
+        assertEquals(adjust(adjuster, 0.0), -0.5);
+    }
+}
+\ No newline at end of file