Cover invalid selector with some tests

DEVSIX-6158

Author: ars18wrw

styled-xml-parser/src/main/java/com/itextpdf/styledxmlparser/css/parse/CssSelectorParser.java

@@ -43,6 +43,7 @@ This file is part of the iText (R) project.
 package com.itextpdf.styledxmlparser.css.parse;
 
 import com.itextpdf.commons.utils.MessageFormatUtil;
+import com.itextpdf.styledxmlparser.exceptions.StyledXmlParserExceptionMessage;
 import com.itextpdf.styledxmlparser.logs.StyledXmlParserLogMessageConstant;
 import com.itextpdf.styledxmlparser.css.selector.item.CssAttributeSelectorItem;
 import com.itextpdf.styledxmlparser.css.selector.item.CssClassSelectorItem;
@@ -129,7 +130,9 @@ public static List<ICssSelectorItem> parseSelectorItems(String selector) {
                 case '>':
                 case '~':
                     if (selectorItems.size() == 0) {
-                        throw new IllegalArgumentException(MessageFormatUtil.format("Invalid token detected in the start of the selector string: {0}", firstChar));
+                        throw new IllegalArgumentException(MessageFormatUtil.format(
+                                StyledXmlParserExceptionMessage.INVALID_TOKEN_AT_THE_BEGINNING_OF_SELECTOR,
+                                firstChar));
                     }
                     ICssSelectorItem lastItem = selectorItems.get(selectorItems.size() - 1);
                     CssSeparatorSelectorItem curItem = new CssSeparatorSelectorItem(firstChar);

styled-xml-parser/src/main/java/com/itextpdf/styledxmlparser/exceptions/StyledXmlParserExceptionMessage.java

@@ -26,6 +26,8 @@ This file is part of the iText (R) project.
  * Class containing constants to be used in exceptions in the SXP module.
  */
 public final class StyledXmlParserExceptionMessage {
+    public static final String INVALID_TOKEN_AT_THE_BEGINNING_OF_SELECTOR
+            = "Invalid token detected at the beginning of the selector string: \"{0}\"";
     public static final String READING_BYTE_LIMIT_MUST_NOT_BE_LESS_ZERO = "The reading byte limit argument must not be less than zero.";
 
     private StyledXmlParserExceptionMessage() {

styled-xml-parser/src/test/java/com/itextpdf/styledxmlparser/css/parse/CssSelectorParserTest.java

@@ -0,0 +1,50 @@
+/*
+    This file is part of the iText (R) project.
+    Copyright (c) 1998-2021 iText Group NV
+    Authors: iText Software.
+
+    This program is offered under a commercial and under the AGPL license.
+    For commercial licensing, contact us at https://itextpdf.com/sales.  For AGPL licensing, see below.
+
+    AGPL licensing:
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.itextpdf.styledxmlparser.css.parse;
+
+import com.itextpdf.commons.utils.MessageFormatUtil;
+import com.itextpdf.io.exceptions.IOException;
+import com.itextpdf.styledxmlparser.exceptions.StyledXmlParserExceptionMessage;
+import com.itextpdf.test.ExtendedITextTest;
+import com.itextpdf.test.annotations.type.UnitTest;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+
+@Category(UnitTest.class)
+public class CssSelectorParserTest extends ExtendedITextTest {
+
+    @Test
+    public void selectorBeginsWithSpaceTest() throws IOException {
+        String space = " ";
+        String selectorWithSpaceAtTheBeginning = space + ".spaceBefore";
+
+        Exception expectedException = Assert.assertThrows(IllegalArgumentException.class,
+                () -> CssSelectorParser.parseSelectorItems(selectorWithSpaceAtTheBeginning));
+        Assert.assertEquals(
+                MessageFormatUtil.format(StyledXmlParserExceptionMessage.INVALID_TOKEN_AT_THE_BEGINNING_OF_SELECTOR,
+                        space),
+                expectedException.getMessage());
+    }
+}