tests/search_match_inference: add more cases

test/search/search_match_inference_test.dart

@@ -191,4 +191,67 @@ void main() {
       ),
     ]);
   });
+
+  test('Infer match with no matches', () {
+    final wordSearchResult = WordSearchResult(
+      entryId: 0,
+      score: 0,
+      isCommon: false,
+      jlptLevel: JlptLevel.none,
+      kanjiInfo: {},
+      readingInfo: {},
+      japanese: [WordSearchRuby(base: '仮名', furigana: 'かな')],
+      senses: [
+        WordSearchSense(
+          antonyms: [],
+          dialects: [],
+          englishDefinitions: ['kana'],
+          fields: [],
+          info: [],
+          languageSource: [],
+          misc: [],
+          partsOfSpeech: [],
+          restrictedToKanji: [],
+          restrictedToReading: [],
+          seeAlso: [],
+        ),
+      ],
+      sources: WordSearchSources.empty(),
+    );
+
+    wordSearchResult.inferMatchSpans('xyz');
+
+    expect(wordSearchResult.matchSpans, isEmpty);
+  });
+
+  test('Infer multiple matches of same substring', () {
+    final wordSearchResult = WordSearchResult(
+      entryId: 0,
+      score: 0,
+      isCommon: false,
+      jlptLevel: JlptLevel.none,
+      kanjiInfo: {},
+      readingInfo: {},
+      japanese: [WordSearchRuby(base: 'ああ')],
+      senses: [],
+      sources: WordSearchSources.empty(),
+    );
+
+    wordSearchResult.inferMatchSpans('あ');
+
+    expect(wordSearchResult.matchSpans, [
+      WordSearchMatchSpan(
+        spanType: WordSearchMatchSpanType.kanji,
+        start: 0,
+        end: 1,
+        index: 0,
+      ),
+      WordSearchMatchSpan(
+        spanType: WordSearchMatchSpanType.kanji,
+        start: 1,
+        end: 2,
+        index: 0,
+      ),
+    ]);
+  });
 }