From 390b864ff385b25483e80806098bc1ad27b44441 Mon Sep 17 00:00:00 2001
From: Ashley Frieze <ashley@incredible.org.uk>
Date: Fri, 20 Nov 2020 17:44:42 +0000
Subject: [PATCH] BAEL-4742-Guide-To-System-Stubs

---
 testing-modules/testing-libraries-2/pom.xml   | 41 ++++++++++++++++
 .../SystemLambdaComparisonUnitTest.java       | 49 +++++++++++++++++++
 2 files changed, 90 insertions(+)
 create mode 100644 testing-modules/testing-libraries-2/src/test/java/com/baeldung/systemstubs/SystemLambdaComparisonUnitTest.java

diff --git a/testing-modules/testing-libraries-2/pom.xml b/testing-modules/testing-libraries-2/pom.xml
index 282583c882..dd863af6ee 100644
--- a/testing-modules/testing-libraries-2/pom.xml
+++ b/testing-modules/testing-libraries-2/pom.xml
@@ -9,6 +9,7 @@
         <groupId>com.baeldung</groupId>
         <artifactId>testing-modules</artifactId>
         <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>
@@ -24,6 +25,44 @@
             <version>${system-lambda.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>uk.org.webcompere</groupId>
+            <artifactId>system-stubs-jupiter</artifactId>
+            <version>${system-stubs.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>uk.org.webcompere</groupId>
+            <artifactId>system-stubs-junit4</artifactId>
+            <version>${system-stubs.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- System Stubs requires more up to date JUnit 5 -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -39,5 +78,7 @@
     <properties>
         <system-rules.version>1.19.0</system-rules.version>
         <system-lambda.version>1.0.0</system-lambda.version>
+        <system-stubs.version>1.0.0</system-stubs.version>
+        <junit.jupiter.version>5.6.2</junit.jupiter.version>
     </properties>
 </project>
diff --git a/testing-modules/testing-libraries-2/src/test/java/com/baeldung/systemstubs/SystemLambdaComparisonUnitTest.java b/testing-modules/testing-libraries-2/src/test/java/com/baeldung/systemstubs/SystemLambdaComparisonUnitTest.java
new file mode 100644
index 0000000000..23e65767a8
--- /dev/null
+++ b/testing-modules/testing-libraries-2/src/test/java/com/baeldung/systemstubs/SystemLambdaComparisonUnitTest.java
@@ -0,0 +1,49 @@
+package com.baeldung.systemstubs;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import uk.org.webcompere.systemstubs.environment.EnvironmentVariables;
+import uk.org.webcompere.systemstubs.jupiter.SystemStub;
+import uk.org.webcompere.systemstubs.jupiter.SystemStubsExtension;
+import uk.org.webcompere.systemstubs.properties.SystemProperties;
+
+import static com.github.stefanbirkner.systemlambda.SystemLambda.restoreSystemProperties;
+import static com.github.stefanbirkner.systemlambda.SystemLambda.withEnvironmentVariable;
+import static org.junit.Assert.assertEquals;
+
+@ExtendWith(SystemStubsExtension.class)
+class SystemLambdaComparisonUnitTest {
+    @SystemStub
+    private EnvironmentVariables environmentVariables =
+      new EnvironmentVariables("ADDRESS", "https://www.baeldung.com");
+
+    @SystemStub
+    private SystemProperties systemProperties = new SystemProperties();
+
+    @Test
+    void aSingleSystemLambda() throws Exception {
+        restoreSystemProperties(() -> {
+            System.setProperty("log_dir", "test/resources");
+            assertEquals("test/resources", System.getProperty("log_dir"));
+        });
+    }
+
+    @Test
+    void multipleSystemLambdas() throws Exception {
+        restoreSystemProperties(() -> {
+            withEnvironmentVariable("URL", "https://www.baeldung.com")
+                .execute(() -> {
+                    System.setProperty("log_dir", "test/resources");
+                    assertEquals("test/resources", System.getProperty("log_dir"));
+                    assertEquals("https://www.baeldung.com", System.getenv("URL"));
+                });
+        });
+    }
+
+    @Test
+    void multipleSystemStubs() {
+        System.setProperty("log_dir", "test/resources");
+        assertEquals("test/resources", System.getProperty("log_dir"));
+        assertEquals("https://www.baeldung.com", System.getenv("ADDRESS"));
+    }
+}