NativeRegExp: add a few unit tests for lookbehind

mozilla · Feb 25, 2025 · 38d265d · 38d265d
1 parent 79f3bed
commit 38d265d
Showing 1 changed file with 90 additions and 0 deletions.
diff --git a/rhino/src/test/java/org/mozilla/javascript/tests/NativeRegExpTest.java b/rhino/src/test/java/org/mozilla/javascript/tests/NativeRegExpTest.java
@@ -553,4 +553,94 @@ public void objectToString() throws Exception {
                 "TypeError: Method \"toString\" called on incompatible object",
                 "var toString = RegExp.prototype.toString; try { toString(); } catch (e) { ('' + e).substr(0, 58) }");
     }
+
+    @Test
+    public void lookbehindPositive() throws Exception {
+        // matches numbers that are preceded by a dollar sign
+        final String script = "var regex = /(?<=\\$)\\d+/g;\n"
+                + "var result = '$123 $456 789'.match(regex);\n"
+                + "var res = '' + result.length;\n"
+                + "res = res + '-' + result[0];\n"
+                + "res = res + '-' + result[1];\n"
+                + "res;";
+        Utils.assertWithAllModes_ES6("2-123-456", script);
+    }
+
+    @Test
+    public void lookbehindNegative() throws Exception {
+        // matches numbers that are not preceded by a dollar sign
+        final String script = "var regex = /(?<!\\$)\\d/g;\n"
+                + "var result = '$1 $4 7'.match(regex);\n"
+                + "var res = '' + result.length;\n"
+                + "res = res + '-' + result[0];\n"
+                + "res;";
+        Utils.assertWithAllModes_ES6("1-7", script);
+    }
+
+    @Test
+    public void lookbehindCapture() throws Exception {
+        // This shows that the lookbehind matches the input backwards
+        // this is why, the second capture group is 'bc' and not 'c'
+        final String script = "var regex = /(?<=([ab]+)([bc]+))$/;\n"
+                + "var result = 'abc'.match(regex);\n"
+                + "var res = '' + result.length;\n"
+                + "res = res + '-' + result[1];\n"
+                + "res = res + '-' + result[2];\n"
+                + "res;";
+        Utils.assertWithAllModes_ES6("3-a-bc", script);
+    }
+
+    @Test
+    public void lookbehindQuantifiedCapture() throws Exception {
+        // When a lookbehind has quantified capture groups, the left-most match is captured
+        final String script = "var regex = /(?<=(\\d)+)a/;\n"
+                + "var result = '123a'.match(regex);\n"
+                + "var res = '' + result.length;\n"
+                + "res = res + '-' + result[0];\n"
+                + "res = res + '-' + result[1];\n"
+                + "res;";
+        Utils.assertWithAllModes_ES6("2-a-1", script);
+    }
+
+    @Test
+    public void lookbehindBackreference2() throws Exception {
+        final String script = "var regex = /(?<=(\\2)x(.))y/;\n"
+                + "var result = '4x4y'.match(regex);\n"
+                + "var res = '' + result.length;\n"
+                + "res = res + '-' + result[0];\n"
+                + "res = res + '-' + result[1];\n"
+                + "res = res + '-' + result[2];\n"
+                + "res;";
+        Utils.assertWithAllModes_ES6("3-y-4-4", script);
+    }
+
+    @Test
+    public void lookbehindNested() throws Exception {
+        // lookbehind inside a lookbehind matches the input backwards
+        final String script = "var regex = /(?<=([ab]+)([bc]+)(?<=([ab]+)([bc]+)))$/;\n"
+                + "var result = 'abcabc'.match(regex);\n"
+                + "var res = '' + result.length;\n"
+                + "res = res + '-' + result[0];\n"
+                + "res = res + '-' + result[1];\n"
+                + "res = res + '-' + result[2];\n"
+                + "res = res + '-' + result[3];\n"
+                + "res = res + '-' + result[4];\n"
+                + "res;";
+        Utils.assertWithAllModes_ES6("5--a-bc-a-bc", script);
+    }
+
+    @Test
+    public void lookbehindLookahead() throws Exception {
+        // lookahead inside a lookbehind matches forward
+        final String script = "var regex = /(?<=([ab]+)([bc]+)(?=([xy]+)([yz]+)))/;\n"
+                + "var result = 'abcxyz'.match(regex);\n"
+                + "var res = '' + result.length;\n"
+                + "res = res + '-' + result[0];\n"
+                + "res = res + '-' + result[1];\n"
+                + "res = res + '-' + result[2];\n"
+                + "res = res + '-' + result[3];\n"
+                + "res = res + '-' + result[4];\n"
+                + "res;";
+        Utils.assertWithAllModes_ES6("5--a-bc-xy-z", script);
+    }
 }