Make version parsing in JUnit4VersionCheck more lenient

Prior to this commit, JUnit4VersionCheck failed to parse custom JUnit 4
version IDs if they did not match the pattern #.# (e.g., 4.12, 4.13,
etc.).

This commit relaxes the regular expression used to parse version IDs in
order to support custom version ID formats such as `4.12.0`,
`4.12-patch_1`, etc.

Closes #2198

Author: sbrannen

documentation/src/docs/asciidoc/release-notes/release-notes-5.6.3.adoc

@@ -27,4 +27,6 @@ No changes.
 
 ==== Bug Fixes
 
-* ❓
+* The internal `JUnit4VersionCheck` class -- which verifies that a supported version of
+  JUnit 4 is on the classpath -- now implements a lenient version ID parsing algorithm in
+  order to support custom version ID formats such as `4.13.1`, `4.13-patch_1`, etc.

junit-vintage-engine/src/main/java/org/junit/vintage/engine/JUnit4VersionCheck.java

@@ -25,7 +25,7 @@
  */
 class JUnit4VersionCheck {
 
-	private static final Pattern versionPattern = Pattern.compile("^(\\d+\\.\\d+)(?:-.+)?");
+	private static final Pattern versionPattern = Pattern.compile("^(\\d+\\.\\d+).*");
 	private static final BigDecimal minVersion = new BigDecimal("4.12");
 
 	static void checkSupported() {

junit-vintage-engine/src/test/java/org/junit/vintage/engine/JUnit4VersionCheckTests.java

@@ -10,6 +10,7 @@
 
 package org.junit.vintage.engine;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -22,6 +23,35 @@
  */
 class JUnit4VersionCheckTests {
 
+	/**
+	 * @since 5.7
+	 */
+	@Test
+	void handlesParsingSupportedVersionIdWithStandardVersionFormat() {
+		assertDoesNotThrow(() -> JUnit4VersionCheck.checkSupported(() -> "4.12"));
+		assertDoesNotThrow(() -> JUnit4VersionCheck.checkSupported(() -> "4.13"));
+	}
+
+	/**
+	 * @since 5.7
+	 */
+	@Test
+	void handlesParsingSupportedVersionIdWithCustomizedVersionFormat() {
+		assertDoesNotThrow(() -> JUnit4VersionCheck.checkSupported(() -> "4.12-patch_1"));
+		assertDoesNotThrow(() -> JUnit4VersionCheck.checkSupported(() -> "4.12.0"));
+		assertDoesNotThrow(() -> JUnit4VersionCheck.checkSupported(() -> "4.12.0.1"));
+		assertDoesNotThrow(() -> JUnit4VersionCheck.checkSupported(() -> "4.12.0.patch-042"));
+	}
+
+	@Test
+	void throwsExceptionForUnsupportedVersion() {
+		JUnitException exception = assertThrows(JUnitException.class,
+			() -> JUnit4VersionCheck.checkSupported(() -> "4.11"));
+
+		assertEquals("Unsupported version of junit:junit: 4.11. Please upgrade to version 4.12 or later.",
+			exception.getMessage());
+	}
+
 	@Test
 	void handlesErrorsReadingVersion() {
 		Error error = new NoClassDefFoundError();
@@ -42,13 +72,4 @@ void handlesErrorsParsingVersion() {
 		assertEquals("Failed to parse version of junit:junit: not a version", exception.getMessage());
 	}
 
-	@Test
-	void throwsExceptionOnUnsupportedVersion() {
-		JUnitException exception = assertThrows(JUnitException.class,
-			() -> JUnit4VersionCheck.checkSupported(() -> "4.11"));
-
-		assertEquals("Unsupported version of junit:junit: 4.11. Please upgrade to version 4.12 or later.",
-			exception.getMessage());
-	}
-
 }