Add regression test for strftime timezone mismatch

Author: timfel

graalpython/com.oracle.graal.python.test/src/com/oracle/graal/python/test/builtin/modules/TimeModuleTests.java

@@ -0,0 +1,97 @@
+/*
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+package com.oracle.graal.python.test.builtin.modules;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.TimeZone;
+
+import org.graalvm.polyglot.Context;
+import org.graalvm.polyglot.Source;
+import org.junit.Test;
+
+public class TimeModuleTests {
+
+    @Test
+    public void strftimeTimezoneMatchesTzsetState() {
+        TimeZone previousDefault = TimeZone.getDefault();
+        try {
+            TimeZone.setDefault(TimeZone.getTimeZone("Europe/Berlin"));
+            String result;
+            try (Context context = Context.newBuilder("python").allowAllAccess(true).build()) {
+                result = context.eval(Source.create("python", """
+                                import os
+                                import time
+
+                                os.environ["TZ"] = "UTC"
+                                time.tzset()
+                                tt = time.localtime()
+
+                                "\\n".join((
+                                    f"tm_zone={tt.tm_zone}",
+                                    f"tzname={time.tzname[tt.tm_isdst > 0]}",
+                                    f"strftime_tuple={time.strftime('%Z', tt)}",
+                                    f"strftime_now={time.strftime('%Z')}",
+                                ))
+                                """)).asString();
+            }
+
+            Map<String, String> values = parseKeyValueLines(result);
+            String details = values.toString();
+            assertEquals(details, values.get("tm_zone"), values.get("tzname"));
+            assertEquals(details, values.get("tm_zone"), values.get("strftime_tuple"));
+            assertEquals(details, values.get("tm_zone"), values.get("strftime_now"));
+        } finally {
+            TimeZone.setDefault(previousDefault);
+        }
+    }
+
+    private static Map<String, String> parseKeyValueLines(String output) {
+        Map<String, String> values = new LinkedHashMap<>();
+        for (String line : output.split("\\R")) {
+            int separator = line.indexOf('=');
+            values.put(line.substring(0, separator), line.substring(separator + 1));
+        }
+        return values;
+    }
+}