From b115d851bd173c6f7c320b0e07e8297ead464301 Mon Sep 17 00:00:00 2001
From: Liam Harwood <lharwood@hubspot.com>
Date: Mon, 29 Apr 2019 15:41:21 -0400
Subject: [PATCH] Add a warning when there is no matching start tag for an end
 tag

---
 .../java/com/hubspot/jinjava/tree/TreeParser.java  | 14 ++++++++++++++
 .../com/hubspot/jinjava/tree/TreeParserTest.java   | 11 +++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/main/java/com/hubspot/jinjava/tree/TreeParser.java b/src/main/java/com/hubspot/jinjava/tree/TreeParser.java
index d77abe1b5..466213a74 100644
--- a/src/main/java/com/hubspot/jinjava/tree/TreeParser.java
+++ b/src/main/java/com/hubspot/jinjava/tree/TreeParser.java
@@ -199,11 +199,13 @@ private void endTag(Tag tag, TagToken tagToken) {
       parent.getMaster().setRightTrimAfterEnd(tagToken.isRightTrim());
     }
 
+    boolean hasMatchingStartTag = false;
     while (!(parent instanceof RootNode)) {
       TagNode parentTag = (TagNode) parent;
       parent = parent.getParent();
 
       if (parentTag.getEndName().equals(tag.getEndTagName())) {
+        hasMatchingStartTag = true;
         break;
       } else {
         interpreter.addError(TemplateError.fromException(
@@ -212,5 +214,17 @@ private void endTag(Tag tag, TagToken tagToken) {
                                         tagToken.getLineNumber(), tagToken.getStartPosition())));
       }
     }
+    if (!hasMatchingStartTag) {
+      interpreter.addError(new TemplateError(
+          ErrorType.WARNING,
+          ErrorReason.SYNTAX_ERROR,
+          ErrorItem.TAG,
+          "Missing start tag",
+          tag.getName(),
+          tagToken.getLineNumber(),
+          tagToken.getStartPosition(),
+          null
+      ));
+    }
   }
 }
diff --git a/src/test/java/com/hubspot/jinjava/tree/TreeParserTest.java b/src/test/java/com/hubspot/jinjava/tree/TreeParserTest.java
index ec1f8e887..0c56944bd 100644
--- a/src/test/java/com/hubspot/jinjava/tree/TreeParserTest.java
+++ b/src/test/java/com/hubspot/jinjava/tree/TreeParserTest.java
@@ -11,6 +11,7 @@
 import com.hubspot.jinjava.Jinjava;
 import com.hubspot.jinjava.JinjavaConfig;
 import com.hubspot.jinjava.interpret.JinjavaInterpreter;
+import com.hubspot.jinjava.interpret.TemplateError.ErrorType;
 
 public class TreeParserTest {
 
@@ -86,6 +87,16 @@ public void trimAndLstripBlocks() {
             + "</div>\n");
   }
 
+  @Test
+  public void itWarnsAgainstMissingStartTags() {
+    String expression = "{% if true %} foo {% endif %} {% endif %}";
+    final Node tree = new TreeParser(interpreter, expression).buildTree();
+    assertThat(interpreter.getErrors()).hasSize(1);
+    assertThat(interpreter.getErrors().get(0).getSeverity()).isEqualTo(ErrorType.WARNING);
+    assertThat(interpreter.getErrors().get(0).getMessage()).isEqualTo("Missing start tag");
+    assertThat(interpreter.getErrors().get(0).getFieldName()).isEqualTo("endif");
+  }
+
   Node parse(String fixture) {
     try {
       return new TreeParser(interpreter, Resources.toString(