script_score query errors on negative scores

7.5 and 7.6 had a regression that allowed for
script_score queries to have negative scores.
We have corrected this regression in elastic#52478.
This is an addition to elastic#52478 that adds
a test and release notes.

docs/reference/release-notes/7.7.asciidoc

@@ -11,3 +11,8 @@ Mapping::
 * Dynamic mappings in indices created on 8.0 and later have stricter validation at mapping update time and
   results in a deprecation warning for indices created in Elasticsearch 7.7.0 and later.
   (e.g. incorrect analyzer settings or unknown field types). {pull}51233[#51233]
+
+Search::
+* A regression that allowed negative scores in a script_score query was corrected.
+A behaviour is restored that throws an error if script_score query produces
+a negative score {pull}52478[#52478].

modules/lang-painless/src/test/resources/rest-api-spec/test/painless/120_script_score_negative_score.yml

@@ -0,0 +1,37 @@
+# Integration tests for ScriptScoreQuery using Painless
+setup:
+  - skip:
+      version: " - 7.6.99"
+      reason: "script_score negative score was not allowed again from 7.7"
+  - do:
+      indices.create:
+        index: test_index
+        body:
+          settings:
+            index:
+              number_of_shards: 1
+              number_of_replicas: 0
+          mappings:
+            properties:
+              k:
+                type: keyword
+
+  - do:
+      index:
+        index: test_index
+        id: 1
+        body: { "k": "value" }
+        refresh: true
+
+---
+"script_score should error on negative score":
+    - do:
+        catch: /.*script_score script returned an invalid score \[-1000.0\] for doc \[0\].*/
+        search:
+          index: test_index
+          body:
+            query:
+              script_score:
+                query: {match_all: {}}
+                script:
+                  source: "-1000"