Adding highlighter yaml tests for empty input

Author: Samiul-TheSoccerFan

x-pack/plugin/inference/src/yamlRestTest/resources/rest-api-spec/test/inference/90_semantic_text_highlighter.yml

@@ -291,3 +291,108 @@ setup:
   - match:      { hits.hits.0._id: "doc_1" }
   - not_exists: hits.hits.0.highlight.title
 
+---
+"Highlighting and multi chunks with empty input":
+  - requires:
+      cluster_features: "semantic_text.handle_empty_input"
+      reason: skips generating embeddings when semantic_text field is contains empty or whitespace only input
+
+  - do:
+      indices.create:
+        index: test-multi-chunk-index
+        body:
+          settings:
+            index.mapping.semantic_text.use_legacy_format: false
+          mappings:
+            properties:
+              semantic_text_field:
+                type: semantic_text
+                inference_id: sparse-inference-id
+
+  - do:
+      index:
+        index: test-multi-chunk-index
+        id: doc_1
+        body:
+          semantic_text_field: ["some test data", "    ", "now with chunks"]
+        refresh: true
+
+  - do:
+      search:
+        index: test-multi-chunk-index
+        body:
+          query:
+            semantic:
+              field: "semantic_text_field"
+              query: "test"
+          highlight:
+            fields:
+              semantic_text_field:
+                type: "semantic"
+                number_of_fragments: 1
+
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "doc_1" }
+  - length: { hits.hits.0.highlight.semantic_text_field: 1 }
+  - match: { hits.hits.0.highlight.semantic_text_field.0: "now with chunks" }
+
+  - do:
+      search:
+        index: test-multi-chunk-index
+        body:
+          query:
+            semantic:
+              field: "semantic_text_field"
+              query: "test"
+          highlight:
+            fields:
+              semantic_text_field:
+                type: "semantic"
+                number_of_fragments: 2
+
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "doc_1" }
+  - length: { hits.hits.0.highlight.semantic_text_field: 2}
+  - match: { hits.hits.0.highlight.semantic_text_field.0: "some test data" }
+  - match: { hits.hits.0.highlight.semantic_text_field.1: "now with chunks" }
+
+  - do:
+      search:
+        index: test-multi-chunk-index
+        body:
+          query:
+            semantic:
+              field: "semantic_text_field"
+              query: "test"
+          highlight:
+            fields:
+              semantic_text_field:
+                type: "semantic"
+                order: "score"
+                number_of_fragments: 1
+
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "doc_1" }
+  - length: { hits.hits.0.highlight.semantic_text_field: 1 }
+  - match: { hits.hits.0.highlight.semantic_text_field.0: "now with chunks" }
+
+  - do:
+      search:
+        index: test-multi-chunk-index
+        body:
+          query:
+            semantic:
+              field: "semantic_text_field"
+              query: "test"
+          highlight:
+            fields:
+              semantic_text_field:
+                type: "semantic"
+                order: "score"
+                number_of_fragments: 2
+
+  - match: { hits.total.value: 1 }
+  - match: { hits.hits.0._id: "doc_1" }
+  - length: { hits.hits.0.highlight.semantic_text_field: 2}
+  - match: { hits.hits.0.highlight.semantic_text_field.0: "now with chunks" }
+  - match: { hits.hits.0.highlight.semantic_text_field.1: "some test data" }