Add warnings for unclosed tokens.

Fixes #1038 and #373

src/main/java/com/hubspot/jinjava/tree/TreeParser.java

@@ -36,6 +36,7 @@
 import com.hubspot.jinjava.tree.parse.Token;
 import com.hubspot.jinjava.tree.parse.TokenScanner;
 import com.hubspot.jinjava.tree.parse.TokenScannerSymbols;
+import com.hubspot.jinjava.tree.parse.UnclosedToken;
 import org.apache.commons.lang3.StringUtils;
 
 public class TreeParser {
@@ -97,6 +98,20 @@ private Node nextNode() {
     Token token = scanner.next();
 
     if (token.getType() == symbols.getFixed()) {
+      if (token instanceof UnclosedToken) {
+        interpreter.addError(
+          new TemplateError(
+            ErrorType.WARNING,
+            ErrorReason.SYNTAX_ERROR,
+            ErrorItem.TAG,
+            "Unclosed token",
+            "token",
+            token.getLineNumber(),
+            token.getStartPosition(),
+            null
+          )
+        );
+      }
       return text((TextToken) token);
     } else if (token.getType() == symbols.getExprStart()) {
       return expression((ExpressionToken) token);

src/main/java/com/hubspot/jinjava/tree/parse/TokenScanner.java

@@ -229,6 +229,14 @@ private Token getEndToken() {
     if (inComment > 0) {
       type = symbols.getNote();
     }
+    if (inBlock > 0) {
+      return new UnclosedToken(
+        String.valueOf(is, tokenStart, tokenLength),
+        currLine,
+        tokenStart - lastNewlinePos + 1,
+        symbols
+      );
+    }
     return Token.newToken(
       type,
       symbols,

src/main/java/com/hubspot/jinjava/tree/parse/UnclosedToken.java

@@ -0,0 +1,13 @@
+package com.hubspot.jinjava.tree.parse;
+
+public class UnclosedToken extends TextToken {
+
+  public UnclosedToken(
+    String image,
+    int lineNumber,
+    int startPosition,
+    TokenScannerSymbols symbols
+  ) {
+    super(image, lineNumber, startPosition, symbols);
+  }
+}

src/test/java/com/hubspot/jinjava/tree/TreeParserTest.java

@@ -164,6 +164,29 @@ public void itWarnsAgainstUnclosedComment() {
     assertThat(interpreter.getErrors().get(0).getFieldName()).isEqualTo("comment");
   }
 
+  @Test
+  public void itWarnsAgainstUnclosedExpression() {
+    String expression = "foo {{ this is an unclosed expression %}";
+    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("Unclosed token");
+    assertThat(interpreter.getErrors().get(0).getFieldName()).isEqualTo("token");
+    assertThat(interpreter.render(tree))
+      .isEqualTo("foo {{ this is an unclosed expression %}");
+  }
+
+  @Test
+  public void itWarnsAgainstUnclosedTag() {
+    String expression = "foo {% this is an unclosed tag }}";
+    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("Unclosed token");
+    assertThat(interpreter.getErrors().get(0).getFieldName()).isEqualTo("token");
+    assertThat(interpreter.render(tree)).isEqualTo("foo {% this is an unclosed tag }}");
+  }
+
   @Test
   public void itWarnsTwiceAgainstUnclosedForTag() {
     String expression = "{% for item in list %}\n{% for elem in items %}";