SystemEnvironmentPropertySource uses actual SecurityManager check and direct keySet access

Issue: SPR-12224

spring-core/src/test/java/org/springframework/core/env/SystemEnvironmentPropertySourceTests.java

@@ -17,7 +17,9 @@
 package org.springframework.core.env;
 
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -29,19 +31,23 @@ import static org.junit.Assert.*;
  * Unit tests for {@link SystemEnvironmentPropertySource}.
  *
  * @author Chris Beams
+ * @author Juergen Hoeller
  * @since 3.1
  */
 public class SystemEnvironmentPropertySourceTests {
 
 	private Map<String, Object> envMap;
+
 	private PropertySource<?> ps;
 
+
 	@Before
 	public void setUp() {
 		envMap = new HashMap<String, Object>();
 		ps = new SystemEnvironmentPropertySource("sysEnv", envMap);
 	}
 
+
 	@Test
 	public void none() {
 		assertThat(ps.containsProperty("a.key"), equalTo(false));
@@ -107,9 +113,20 @@ public class SystemEnvironmentPropertySourceTests {
 			public boolean containsKey(Object key) {
 				throw new UnsupportedOperationException();
 			}
+			@Override
+			public Set<String> keySet() {
+				return new HashSet<String>(super.keySet());
+			}
 		};
-		ps = new SystemEnvironmentPropertySource("sysEnv", envMap);
 		envMap.put("A_KEY", "a_value");
+
+		ps = new SystemEnvironmentPropertySource("sysEnv", envMap) {
+			@Override
+			protected boolean isSecurityManagerPresent() {
+				return true;
+			}
+		};
+
 		assertThat(ps.containsProperty("A_KEY"), equalTo(true));
 		assertThat(ps.getProperty("A_KEY"), equalTo((Object)"a_value"));
 	}