Merge pull request #68 from webcompere/interoperability-with-other-libraries

Provide backwards compatibility for tools that should be able to mock the environment

Author: ashleyfrieze

system-stubs-core/src/main/java/uk/org/webcompere/systemstubs/environment/EnvironmentVariableMocker.java

@@ -30,7 +30,7 @@ public class EnvironmentVariableMocker {
     private static final Map<String, String> ORIGINAL_ENV;
 
     static {
-        ORIGINAL_ENV = System.getenv();
+        ORIGINAL_ENV = new HashMap<>(System.getenv());
         try {
             Instrumentation instrumentation = ByteBuddyAgent.install();
             installInterceptorIntoBootLoader(instrumentation);

system-stubs-core/src/test/java/uk/org/webcompere/systemstubs/PropertiesFileLoadingTest.java

@@ -16,6 +16,7 @@ void can_load_properties_from_resources() throws Exception {
             new EnvironmentVariables()
                 .set(fromResource("test.properties"))
                 .execute(() -> {
+                   assertThat(System.getenv()).containsEntry("value1", "foo").containsEntry("value2", "bar");
                    assertThat(System.getenv("value1")).isEqualTo("foo");
                    assertThat(System.getenv("value2")).isEqualTo("bar");
                 });

system-stubs-interceptor/src/main/java/uk/org/webcompere/systemstubs/internal/ProcessEnvironmentInterceptor.java

@@ -4,7 +4,7 @@
 
 import java.util.*;
 
-import static java.util.stream.Collectors.toMap;
+import static java.util.stream.Collectors.toSet;
 
 /**
  * Plugs into the boot loader to provide an alternative implementation to ProcessEnvironment
@@ -13,6 +13,9 @@
 public class ProcessEnvironmentInterceptor {
     private static Map<String, String> CURRENT_ENVIRONMENT_VARIABLES = new HashMap<>();
 
+    @SuppressFBWarnings("URF_UNREAD_FIELD")
+    private static Map<String, String> theEnvironment;
+
     /**
      * For use by the EnvironmentMocker - this overwrites the effective environment variables that the system
      * appears to have.
@@ -21,15 +24,19 @@ public class ProcessEnvironmentInterceptor {
     @SuppressFBWarnings("EI_EXPOSE_STATIC_REP2")
     public static void setEnv(Map<String, String> env) {
         CURRENT_ENVIRONMENT_VARIABLES = env;
+
+        // this copy exposes process environment to tools looking to mock it
+        theEnvironment = Collections.unmodifiableMap(CURRENT_ENVIRONMENT_VARIABLES);
     }
 
     /**
      * The equivalent of <code>getenv</code> in the original ProcessEnvironment, assuming that
      * mocking is "turned on"
      * @return the current effective environment
      */
+    @SuppressFBWarnings("MS_EXPOSE_REP")
     public static Map<String, String> getenv() {
-        return filterNulls(CURRENT_ENVIRONMENT_VARIABLES);
+        return Collections.unmodifiableMap(filterNulls(CURRENT_ENVIRONMENT_VARIABLES));
     }
 
     /**
@@ -47,7 +54,7 @@ public static String getenv(String name) {
      * @return the environment map
      */
     public static Map<String, String> environment() {
-        return getenv();
+        return new HashMap<>(getenv());
     }
 
     /**
@@ -129,10 +136,14 @@ public static byte[] toEnvironmentBlock(Map<String, String> m, int[] envc) {
     }
 
     private static Map<String, String> filterNulls(Map<String, String> currentMockedEnvironment) {
-        return currentMockedEnvironment.entrySet()
+        var nullsToRemove = currentMockedEnvironment.entrySet()
             .stream()
-            .filter(entry -> entry.getValue() != null)
-            .collect(toMap(Map.Entry::getKey, Map.Entry::getValue));
+            .filter(entry -> entry.getValue() == null)
+            .map(Map.Entry::getKey)
+            .collect(toSet());
+
+        nullsToRemove.forEach(currentMockedEnvironment::remove);
+        return currentMockedEnvironment;
     }
 
     @SuppressFBWarnings("SE_COMPARATOR_SHOULD_BE_SERIALIZABLE")

system-stubs-jupiter/pom.xml

@@ -45,6 +45,13 @@
       <scope>test</scope>
     </dependency>
 
+    <dependency>
+      <groupId>org.junit-pioneer</groupId>
+      <artifactId>junit-pioneer</artifactId>
+      <version>2.1.0</version>
+      <scope>test</scope>
+    </dependency>
+
     <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-web</artifactId>

system-stubs-jupiter/src/test/java/uk/org/webcompere/systemstubs/jupiter/compatibility/DoesNotPreventJUnitPioneerFromWorkingTest.java

@@ -0,0 +1,41 @@
+package uk.org.webcompere.systemstubs.jupiter.compatibility;
+
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junitpioneer.jupiter.SetEnvironmentVariable;
+import uk.org.webcompere.systemstubs.environment.EnvironmentVariables;
+import uk.org.webcompere.systemstubs.jupiter.SystemStub;
+import uk.org.webcompere.systemstubs.jupiter.SystemStubsExtension;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@EnabledForJreRange(max = JRE.JAVA_16)
+class DoesNotPreventJUnitPioneerFromWorkingTest {
+
+    @Nested
+    @ExtendWith(SystemStubsExtension.class)
+    static class StubsWorks {
+        @SystemStub
+        private EnvironmentVariables variables;
+
+        @Test
+        void canStubVariable() {
+            variables.set("MACHINE", "hot");
+
+            assertThat(System.getenv("MACHINE")).isEqualTo("hot");
+        }
+    }
+
+    @Nested
+    @SetEnvironmentVariable(key="MACHINE", value="COLD")
+    static class PioneerWorks {
+        @Test
+        void canPioneerVariable() {
+            assertThat(System.getenv("MACHINE")).isEqualTo("cold");
+        }
+    }
+
+}