use Locale.ENGLISH when parsing dates in Converter.DATE

src/main/java/org/apache/commons/cli/Converter.java

@@ -24,6 +24,7 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 import java.nio.file.Paths;
 import java.text.SimpleDateFormat;
 import java.util.Date;
+import java.util.Locale;
 
 /**
  * The definition of the functional interface to call when doing a conversion. Like {@code Function<String,T>} but can throw an Exception.
@@ -76,7 +77,7 @@ public interface Converter<T, E extends Exception> {
     /**
      * Converts to a date using the format string Form "EEE MMM dd HH:mm:ss zzz yyyy".
      */
-    Converter<Date, java.text.ParseException> DATE = s -> new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy").parse(s);
+    Converter<Date, java.text.ParseException> DATE = s -> new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy", Locale.ENGLISH).parse(s);
 
     /**
      * Applies the conversion function to the String argument.

src/test/java/org/apache/commons/cli/ConverterTests.java

@@ -26,12 +26,14 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.junitpioneer.jupiter.DefaultLocale;
 
 /**
  * Tests for standard Converters.
@@ -84,13 +86,23 @@ void testDate() throws Exception {
          * time zone.
          */
         final Date expected = new Date(1023400137000L);
-        final DateFormat dateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy");
+        final DateFormat dateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy", Locale.ENGLISH);
         final String formatted = dateFormat.format(expected);
         assertEquals(expected, Converter.DATE.apply(formatted));
 
         assertThrows(java.text.ParseException.class, () -> Converter.DATE.apply("Jun 06 17:48:57 EDT 2002"));
     }
 
+    @Test
+    @DefaultLocale(language = "de", country = "DE")
+    void testDateLocaleIndependent() throws Exception {
+        // Date.toString() always emits English month/day names, so the converter must parse
+        // them even when the JVM default locale is not English.
+        final Date expected = new Date(1023400137000L);
+        final String formatted = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy", Locale.ENGLISH).format(expected);
+        assertEquals(expected, Converter.DATE.apply(formatted));
+    }
+
     @Test
     void testFile() throws Exception {
         final URL url = this.getClass().getClassLoader().getResource("./org/apache/commons/cli/existing-readable.file");

src/test/java/org/apache/commons/cli/PatternOptionBuilderTest.java

@@ -32,6 +32,7 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.Date;
+import java.util.Locale;
 import java.util.Vector;
 
 import org.junit.jupiter.api.Test;
@@ -118,7 +119,7 @@ void testSimplePattern() throws Exception {
          */
         final Options options = PatternOptionBuilder.parsePattern("a:b@cde>f+n%t/m*z#");
         final Date expectedDate = new Date(1023400137000L);
-        final DateFormat dateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy");
+        final DateFormat dateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy", Locale.ENGLISH);
         final String[] args = {"-c", "-a", "foo", "-b", "java.util.Vector", "-e", "build.xml", "-f", "java.util.Calendar", "-n", "4.5", "-t",
             "https://commons.apache.org", "-z", dateFormat.format(expectedDate), "-m", "test*"};
         final CommandLineParser parser = new PosixParser();

src/test/java/org/apache/commons/cli/TypeHandlerTest.java

@@ -38,6 +38,7 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.stream.Stream;
 
@@ -93,7 +94,7 @@ private static Stream<Arguments> createValueTestParameters() throws MalformedURL
          * problem, convert the time into a string and then unparse that using the converter. This produces strings that always match the correct time zone.
          */
         final Date date = new Date(1023400137000L);
-        final DateFormat dateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy");
+        final DateFormat dateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy", Locale.ENGLISH);
 
         list.add(Arguments.of(Instantiable.class.getName(), PatternOptionBuilder.CLASS_VALUE, Instantiable.class));
         list.add(Arguments.of("what ever", PatternOptionBuilder.CLASS_VALUE, ParseException.class));