Fix ordering of property sources on refresh

If there were *no* bootstrapProperties (i.e. properties added by
PropertySourceLocators) on startup, and then in a refresh event
some new sources were picked up, they would have been added to the
end, instead of the beginning of the list.

Fixes https://github.com/spring-cloud/spring-cloud-config/issues/815

spring-cloud-context/src/test/java/org/springframework/cloud/context/refresh/ContextRefresherTests.java

@@ -0,0 +1,96 @@
+package org.springframework.cloud.context.refresh;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.After;
+import org.junit.Test;
+import org.mockito.Mockito;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.test.util.EnvironmentTestUtils;
+import org.springframework.cloud.bootstrap.config.PropertySourceLocator;
+import org.springframework.cloud.context.scope.refresh.RefreshScope;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.env.Environment;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.MutablePropertySources;
+import org.springframework.core.env.PropertySource;
+
+public class ContextRefresherTests {
+
+	private RefreshScope scope = Mockito.mock(RefreshScope.class);
+	private ConfigurableApplicationContext context;
+
+	@After
+	public void close() {
+		if (context != null) {
+			context.close();
+		}
+	}
+
+	@Test
+	public void orderNewPropertiesConsistentWithNewContext() {
+		context = SpringApplication.run(ContextRefresherTests.class,
+				"--spring.main.webEnvironment=false", "--debug=false",
+				"--spring.main.bannerMode=OFF");
+		context.getEnvironment().setActiveProfiles("refresh");
+		List<String> names = names(context.getEnvironment().getPropertySources());
+		assertThat(names).doesNotContain(
+				"applicationConfig: [classpath:/bootstrap-refresh.properties]");
+		ContextRefresher refresher = new ContextRefresher(context, scope);
+		refresher.refresh();
+		names = names(context.getEnvironment().getPropertySources());
+		assertThat(names)
+				.contains("applicationConfig: [classpath:/bootstrap-refresh.properties]");
+		assertThat(names).containsSequence(
+				"applicationConfig: [classpath:/bootstrap-refresh.properties]",
+				"applicationConfig: [classpath:/bootstrap.properties]");
+	}
+
+	@Test
+	public void bootstrapPropertySourceAlwaysFirst() {
+		// Use spring.cloud.bootstrap.name to switch off the defaults (which would pick up
+		// a bootstrapProperties immediately
+		context = SpringApplication.run(ContextRefresherTests.class,
+				"--spring.main.webEnvironment=false", "--debug=false",
+				"--spring.main.bannerMode=OFF", "--spring.cloud.bootstrap.name=refresh");
+		List<String> names = names(context.getEnvironment().getPropertySources());
+		assertThat(names).doesNotContain("bootstrapProperties");
+		ContextRefresher refresher = new ContextRefresher(context, scope);
+		EnvironmentTestUtils.addEnvironment(context,
+				"spring.cloud.bootstrap.sources: org.springframework.cloud.context.refresh.ContextRefresherTests.PropertySourceConfiguration\n"
+						+ "");
+		refresher.refresh();
+		names = names(context.getEnvironment().getPropertySources());
+		assertThat(names).first().isEqualTo("bootstrapProperties");
+	}
+
+	private List<String> names(MutablePropertySources propertySources) {
+		List<String> list = new ArrayList<>();
+		for (PropertySource<?> p : propertySources) {
+			list.add(p.getName());
+		}
+		return list;
+	}
+
+	@Configuration
+	// This is added to bootstrap context as a source in bootstrap.properties
+	protected static class PropertySourceConfiguration implements PropertySourceLocator {
+
+		public static Map<String, Object> MAP = new HashMap<String, Object>(
+				Collections.<String, Object>singletonMap("bootstrap.foo", "refresh"));
+
+		@Override
+		public PropertySource<?> locate(Environment environment) {
+			return new MapPropertySource("refreshTest", MAP);
+		}
+
+	}
+
+}