feat: add WITHIN assertion support to Karate DSL

Add 'within' and '!within' operators to the match DSL syntax:
- Update js.flex lexer to recognize within operators
- Add operator mapping in MatchExpression.getMatchTypeName()
- Update GherkinParser.isMatchOperator() to parse within
- Add parser tests and integration tests in StepMatchTest

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ptrthomas

karate-core/src/test/java/io/karatelabs/core/StepMatchTest.java

@@ -239,4 +239,66 @@ void testMatchEach() {
         assertPassed(sr);
     }
 
+    // ========== Within ==========
+
+    @Test
+    void testMatchWithinArray() {
+        ScenarioRuntime sr = run("""
+            * def subset = [1, 2]
+            * def superset = [1, 2, 3, 4, 5]
+            * match subset within superset
+            """);
+        assertPassed(sr);
+    }
+
+    @Test
+    void testMatchWithinArrayFailure() {
+        ScenarioRuntime sr = run("""
+            * def subset = [1, 6]
+            * def superset = [1, 2, 3, 4, 5]
+            * match subset within superset
+            """);
+        assertFailed(sr);
+    }
+
+    @Test
+    void testMatchWithinMap() {
+        ScenarioRuntime sr = run("""
+            * def subset = { name: 'bar' }
+            * def superset = { name: 'bar', age: 30, city: 'NYC' }
+            * match subset within superset
+            """);
+        assertPassed(sr);
+    }
+
+    @Test
+    void testMatchWithinMapFailure() {
+        ScenarioRuntime sr = run("""
+            * def subset = { name: 'baz' }
+            * def superset = { name: 'bar', age: 30 }
+            * match subset within superset
+            """);
+        assertFailed(sr);
+    }
+
+    @Test
+    void testMatchNotWithin() {
+        ScenarioRuntime sr = run("""
+            * def subset = [7, 8]
+            * def superset = [1, 2, 3]
+            * match subset !within superset
+            """);
+        assertPassed(sr);
+    }
+
+    @Test
+    void testMatchNotWithinFailure() {
+        ScenarioRuntime sr = run("""
+            * def subset = [1, 2]
+            * def superset = [1, 2, 3]
+            * match subset !within superset
+            """);
+        assertFailed(sr);
+    }
+
 }

karate-js/src/main/java/io/karatelabs/gherkin/MatchExpression.java

@@ -79,6 +79,8 @@ public String getMatchTypeName() {
             case "contains only deep" -> "CONTAINS_ONLY_DEEP";
             case "contains any" -> "CONTAINS_ANY";
             case "contains any deep" -> "CONTAINS_ANY_DEEP";
+            case "within" -> "WITHIN";
+            case "!within" -> "NOT_WITHIN";
             default -> throw new RuntimeException("Unknown operator: " + operator);
         };
         return each ? "EACH_" + base : base;

karate-js/src/main/java/io/karatelabs/js/GherkinParser.java

@@ -660,7 +660,8 @@ public static MatchExpression parseMatchExpression(String expression) {
 
     private static boolean isMatchOperator(String text) {
         return text.equals("==") || text.equals("!=") ||
-               text.startsWith("contains") || text.equals("!contains");
+               text.startsWith("contains") || text.equals("!contains") ||
+               text.equals("within") || text.equals("!within");
     }
 
 }

karate-js/src/main/jflex/js.flex

@@ -70,7 +70,7 @@ GM_PREFIX = "*"|"Given"|"When"|"Then"|"And"|"But"
 GM_TYPE_KEYWORD = "def"|"json"|"xml"|"xmlstring"|"yaml"|"csv"|"string"|"bytes"|"copy"
 GM_ASSIGN_KEYWORD = "configure"|"header"|"param"|"cookie"|"form field"|"multipart file"|"multipart field"
 GM_SPACED_KEYWORD = "form fields"|"multipart fields"|"multipart files"|"soap action"|"retry until"|"multipart entity"
-GM_MATCH_TYPE = ("=="|"!="|"contains"|"!contains") ({WS}+("only"|"any"))? ({WS}+"deep")?
+GM_MATCH_TYPE = ("=="|"!="|"contains"|"!contains"|"within"|"!within") ({WS}+("only"|"any"))? ({WS}+"deep")?
 GM_TRIPLE_QUOTE = \"\"\"
 GM_TAG = "@" {NOT_WSLF}+
 

karate-js/src/test/java/io/karatelabs/gherkin/GherkinParserTest.java

@@ -365,4 +365,24 @@ void testParseMatchExpressionWithMethodCall() {
         assertEquals("read('file.txt').replaceAll(\"\\r\", \"\")", me.getExpectedExpr());
     }
 
+    @Test
+    void testParseMatchExpressionWithin() {
+        MatchExpression me = GherkinParser.parseMatchExpression("subset within superset");
+        assertFalse(me.isEach());
+        assertEquals("subset", me.getActualExpr());
+        assertEquals("within", me.getOperator());
+        assertEquals("superset", me.getExpectedExpr());
+        assertEquals("WITHIN", me.getMatchTypeName());
+    }
+
+    @Test
+    void testParseMatchExpressionNotWithin() {
+        MatchExpression me = GherkinParser.parseMatchExpression("foo !within bar");
+        assertFalse(me.isEach());
+        assertEquals("foo", me.getActualExpr());
+        assertEquals("!within", me.getOperator());
+        assertEquals("bar", me.getExpectedExpr());
+        assertEquals("NOT_WITHIN", me.getMatchTypeName());
+    }
+
 }