feat(query): validate depth in sub-boosts passed to Boost.blend

Author: bevzzz

src/main/java/io/weaviate/client6/v1/api/collections/query/Boost.java

@@ -15,6 +15,21 @@ public class Boost {
   private final Float weight;
   private final Integer depth;
 
+  // Package-private for testing.
+  List<Condition> conditions() {
+    return conditions;
+  }
+
+  // Package-private for testing.
+  Float weight() {
+    return weight;
+  }
+
+  // Package-private for testing.
+  Integer depth() {
+    return depth;
+  }
+
   private Boost(Condition condition, Float weight, Integer depth) {
     this(List.of(requireNonNull(condition, "condition")), weight, depth);
   }
@@ -64,6 +79,9 @@ public static Boost filter(Filter filter,
   public static Boost blend(Float weight, Integer depth, Boost... boosts) {
     var conditions = Arrays.stream(boosts)
         .<Condition>mapMulti((b, stream) -> {
+          if (b.depth != null) {
+            throw new IllegalArgumentException("A boost passed to Boosts.blend() cannot set it's own depth.");
+          }
           b.conditions.forEach(cond -> {
             if (cond.weight == null && b.weight != null) {
               cond = cond.withWeight(b.weight);
@@ -103,6 +121,11 @@ private Condition(Object func, Float weight) {
     private Condition withWeight(float weight) {
       return new Condition(func, weight);
     }
+
+    // Package-private for testing.
+    Float weight() {
+      return weight;
+    }
   }
 
   public static class FilterBuilder extends Boost.Builder<FilterBuilder> {

src/test/java/io/weaviate/client6/v1/api/collections/query/BoostTest.java

@@ -0,0 +1,40 @@
+package io.weaviate.client6.v1.api.collections.query;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import io.weaviate.client6.v1.api.collections.query.Boost.Condition;
+
+public class BoostTest {
+  @Test
+  public void test_blend_useConditionWeight() {
+    var boost = Boost.blend(null, 8,
+        Boost.numericProperty("size", prop -> prop.weight(.45f)));
+
+    Assertions.assertThat(boost)
+        .returns(8, Boost::depth)
+        .returns(null, Boost::weight);
+    Assertions.assertThat(boost.conditions()).first()
+        .returns(.45f, Condition::weight);
+  }
+
+  @Test
+  public void test_blend_passWeightToCondition() {
+    var boost = Boost.blend(.45f, 8,
+        Boost.numericProperty("size"));
+
+    Assertions.assertThat(boost)
+        .returns(8, Boost::depth)
+        .returns(.45f, Boost::weight);
+    Assertions.assertThat(boost.conditions()).first()
+        .returns(null, Condition::weight);
+  }
+
+  @Test
+  public void test_blend_illegalDepth() {
+    Assertions.assertThatCode(() -> {
+      Boost.blend(1f, 2,
+          Boost.numericProperty("size", prop -> prop.depth(3)));
+    }).isInstanceOf(IllegalArgumentException.class);
+  }
+}