SCANMAVEN-233 check that sonar.java.jdkHome has default value even without configuration from user (#249)

Author: erwan-serandour

its/projects/jdkHome/defaultValue/pom.xml

@@ -0,0 +1,8 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.sonarsource.it.samples</groupId>
+  <artifactId>extract-jre</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <name>Sonar :: Integration Tests :: Extract Jre</name>
+
+</project>

its/projects/jdkHome/defaultValue/src/main/java/sample/Sample.java

@@ -0,0 +1,12 @@
+package sample;
+
+public class Sample {
+	
+	public Sample(int i) {
+		int j = i++;
+	}
+	
+	public String myMethod() {
+		return "hello";
+	}
+}

its/projects/jdkHome/defaultValue/src/test/java/sample/SampleTest.java

@@ -0,0 +1,12 @@
+package sample;
+
+import org.junit.Test;
+
+public class SampleTest {
+	
+	@Test
+	public void test() {
+	  new Sample(1).myMethod();
+	}
+	
+}

its/src/test/java/com/sonar/maven/it/suite/JavaTest.java

@@ -120,6 +120,26 @@ void setJavaVersionProperties() throws IOException {
       entry("sonar.java.target", "1.8"));
   }
 
+  @Test
+  void when_java_home_exists_it_is_used_as_default_sonar_java_jdkHome_value() throws IOException {
+    //fix value, the plugin should not modify them
+    String javaHomeSystem = System.getProperty("java.home");
+
+    File outputProps = temp.resolve("out.properties").toFile();
+    outputProps.createNewFile();
+    File pom = ItUtils.locateProjectPom("jdkHome/defaultValue");
+
+    MavenBuild build = MavenBuild.create(pom)
+      .setGoals(sonarGoal())
+      .setProperty("sonar.scanner.internal.dumpToFile", outputProps.getAbsolutePath());
+    executeBuildAndValidateWithoutCE(build);
+
+    Properties props = getProps(outputProps);
+    String jdkHome = props.getProperty("sonar.java.jdkHome");
+    //the jdk is not configured in the project, so default value should be used
+    assertThat(jdkHome).isEqualTo(javaHomeSystem);
+  }
+
   @Test
   void setJdkHomeFromCompilerExecutableConfiguration() throws IOException {
     File outputProps = temp.resolve("out.properties").toFile();