spring-projects#282 - Add more unit tests for LikeEscaper

Author: rchigvintsev

Diff for: src/main/java/org/springframework/data/r2dbc/repository/query/LikeEscaper.java

@@ -36,6 +36,10 @@ public class LikeEscaper {
 	private final List<String> toReplace;
 
 	private LikeEscaper(char escapeCharacter) {
+		if (escapeCharacter == '_' || escapeCharacter == '%') {
+			throw new IllegalArgumentException("'_' and '%' are special characters and cannot be used as "
+					+ "escape character");
+		}
 		this.escapeCharacter = escapeCharacter;
 		this.toReplace = Arrays.asList(String.valueOf(escapeCharacter), "_", "%");
 	}
@@ -45,6 +49,7 @@ private LikeEscaper(char escapeCharacter) {
 	 *
 	 * @param escapeCharacter escape character
 	 * @return new instance of {@link LikeEscaper}
+	 * @throws IllegalArgumentException if escape character is one of special characters ('_' and '%')
 	 */
 	public static LikeEscaper of(char escapeCharacter) {
 		return new LikeEscaper(escapeCharacter);

Diff for: src/test/java/org/springframework/data/r2dbc/repository/query/LikeEscaperUnitTests.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.r2dbc.repository.query;
 
+import static org.assertj.core.api.Assertions.*;
 import static org.junit.jupiter.api.Assertions.*;
 
 import org.junit.Test;
@@ -27,4 +28,44 @@ public class LikeEscaperUnitTests {
 	public void ignoresNulls() {
 		assertNull(LikeEscaper.DEFAULT.escape(null));
 	}
+
+	@Test
+	public void ignoresEmptyString() {
+		assertThat(LikeEscaper.DEFAULT.escape("")).isEqualTo("");
+	}
+
+	@Test
+	public void ignoresBlankString() {
+		assertThat(LikeEscaper.DEFAULT.escape(" ")).isEqualTo(" ");
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void throwsExceptionWhenEscapeCharacterIsUnderscore() {
+		LikeEscaper.of('_');
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void throwsExceptionWhenEscapeCharacterIsPercent() {
+		LikeEscaper.of('%');
+	}
+
+	@Test
+	public void escapesUnderscoresUsingDefaultEscapeCharacter() {
+		assertThat(LikeEscaper.DEFAULT.escape("_test_")).isEqualTo("\\_test\\_");
+	}
+
+	@Test
+	public void escapesPercentsUsingDefaultEscapeCharacter() {
+		assertThat(LikeEscaper.DEFAULT.escape("%test%")).isEqualTo("\\%test\\%");
+	}
+
+	@Test
+	public void escapesSpecialCharactersUsingCustomEscapeCharacter() {
+		assertThat(LikeEscaper.of('$').escape("_%")).isEqualTo("$_$%");
+	}
+
+	@Test
+	public void doublesEscapeCharacter() {
+		assertThat(LikeEscaper.DEFAULT.escape("\\")).isEqualTo("\\\\");
+	}
 }