Add toolchain java path to environment variables in ExecMojo

src/main/java/org/codehaus/mojo/exec/ExecMojo.java

@@ -29,6 +29,7 @@
 import java.net.URL;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -338,6 +339,13 @@ public class ExecMojo extends AbstractExecMojo {
     @Parameter(property = "exec.asyncDestroyOnShutdown", defaultValue = "true")
     private boolean asyncDestroyOnShutdown = true;
 
+    /**
+     * @since 3.5.0
+     * Name of environment variable that will contain path to java executable provided by the toolchain (works only if toolchain feature is used)
+     */
+    @Parameter(property = "exec.toolchainJavaHomeEnvName", defaultValue = "TOOLCHAIN_JAVA_HOME")
+    private String toolchainJavaHomeEnvName = "TOOLCHAIN_JAVA_HOME";
+
     @Component
     private ToolchainManager toolchainManager;
 
@@ -488,6 +496,16 @@ private Map<String, String> handleSystemEnvVariables() throws MojoExecutionExcep
             }
         }
 
+        Toolchain tc = getToolchain();
+        if (tc != null && "jdk".equals(tc.getType())) {
+            String toolchainJava = tc.findTool("java");
+            if (toolchainJava != null) {
+                String toolchainJavaHome =
+                        Paths.get(toolchainJava).getParent().getParent().toString();
+                enviro.put(toolchainJavaHomeEnvName, toolchainJavaHome);
+            }
+        }
+
         if (this.getLog().isDebugEnabled()) {
             Set<String> keys = new TreeSet<>(enviro.keySet());
             for (String key : keys) {

src/test/java/org/codehaus/mojo/exec/DummyJdkToolchain.java

@@ -0,0 +1,22 @@
+package org.codehaus.mojo.exec;
+
+import org.apache.maven.toolchain.Toolchain;
+
+public class DummyJdkToolchain implements Toolchain {
+
+    private final String testJavaPath;
+
+    public DummyJdkToolchain(String testJavaPath) {
+        this.testJavaPath = testJavaPath;
+    }
+
+    @Override
+    public String getType() {
+        return "jdk";
+    }
+
+    @Override
+    public String findTool(String s) {
+        return "java".equals(s) ? testJavaPath : null;
+    }
+}

src/test/java/org/codehaus/mojo/exec/ExecMojoTest.java

@@ -12,7 +12,9 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -28,17 +30,21 @@
 import org.apache.maven.execution.MavenSession;
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugin.testing.AbstractMojoTestCase;
-import org.mockito.Mock;
+import org.apache.maven.toolchain.ToolchainManager;
 
 import static java.util.Collections.emptyMap;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 /**
  * @author Jerome Lacoste
  * @version $Id$
  */
 public class ExecMojoTest extends AbstractMojoTestCase {
-    @Mock
-    private MavenSession session;
+    private MavenSession session = mock(MavenSession.class);
+    private ToolchainManager toolchainManager = mock(ToolchainManager.class);
 
     private static final File LOCAL_REPO = new File("src/test/repository");
 
@@ -287,6 +293,40 @@ public void test_exec_receives_all_parameters() throws MojoExecutionException {
                 Paths.get("target", "dist", "mails").toFile().exists());
     }
 
+    public void testToolchainJavaHomePropertySetWhenToolchainIsUsed() throws Exception {
+        // given
+        File basedir;
+        String testJavaPath;
+        File pom;
+
+        if (OS.isFamilyWindows()) {
+            testJavaPath = "\\path\\to\\java\\home";
+            pom = new File(getBasedir(), "src\\test\\projects\\project21\\pom.xml");
+            when(toolchainManager.getToolchainFromBuildContext(any(), eq(session)))
+                    .thenReturn(new DummyJdkToolchain(testJavaPath + "\\bin\\java"));
+        } else {
+            testJavaPath = "/path/to/java/home";
+            pom = new File(getBasedir(), "src/test/projects/project20/pom.xml");
+            when(toolchainManager.getToolchainFromBuildContext(any(), eq(session)))
+                    .thenReturn(new DummyJdkToolchain(testJavaPath + "/bin/java"));
+        }
+
+        ExecMojo execMojo = (ExecMojo) lookupMojo("exec", pom);
+        setVariableValueToObject(execMojo, "session", session);
+        setVariableValueToObject(execMojo, "toolchainManager", toolchainManager);
+
+        basedir = new File("target");
+        execMojo.setBasedir(basedir);
+
+        // when
+        execMojo.execute();
+
+        // then
+        Path resultFilePath = basedir.toPath().resolve("testfile.txt");
+        String result = new String(Files.readAllBytes(resultFilePath), StandardCharsets.UTF_8);
+        assertTrue(result.contains(testJavaPath));
+    }
+
     private void checkMojo(String expectedCommandLine) {
         assertEquals(1, mojo.getAmountExecutedCommandLines());
         CommandLine commandline = mojo.getExecutedCommandline(0);

src/test/projects/project20/pom.xml

@@ -0,0 +1,43 @@
+<project>
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>org.cb.maven.plugins.exec</groupId>
+    <artifactId>project20</artifactId>
+    <version>0.1</version>
+    <packaging>jar</packaging>
+    <name>Maven Exec Plugin</name>
+    <inceptionYear>2005</inceptionYear>
+
+    <licenses>
+        <license>
+            <name>Apache License 2</name>
+            <url>http://www.apache.org/licenses/LICENSE-2.0.txt</url>
+            <distribution>repo</distribution>
+        </license>
+    </licenses>
+
+    <properties>
+        <test.name>${project.artifactId} project</test.name>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <phase>test</phase>
+                        <goals>
+                            <goal>exec</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <toolchainJavaHomeEnvName>CUSTOM_NAME_FOR_TOOLCHAIN_JAVA</toolchainJavaHomeEnvName>
+                    <executable>${basedir}/src/test/projects/project20/testscript.sh</executable>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

src/test/projects/project20/testscript.sh

@@ -0,0 +1 @@
+echo $CUSTOM_NAME_FOR_TOOLCHAIN_JAVA > testfile.txt

src/test/projects/project21/pom.xml

@@ -0,0 +1,43 @@
+<project>
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>org.cb.maven.plugins.exec</groupId>
+    <artifactId>project21</artifactId>
+    <version>0.1</version>
+    <packaging>jar</packaging>
+    <name>Maven Exec Plugin</name>
+    <inceptionYear>2005</inceptionYear>
+
+    <licenses>
+        <license>
+            <name>Apache License 2</name>
+            <url>http://www.apache.org/licenses/LICENSE-2.0.txt</url>
+            <distribution>repo</distribution>
+        </license>
+    </licenses>
+
+    <properties>
+        <test.name>${project.artifactId} project</test.name>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <phase>test</phase>
+                        <goals>
+                            <goal>exec</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <toolchainJavaHomeEnvName>CUSTOM_NAME_FOR_TOOLCHAIN_JAVA</toolchainJavaHomeEnvName>
+                    <executable>${basedir}/src/test/projects/project21/testscript.bat</executable>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

src/test/projects/project21/testscript.bat

@@ -0,0 +1 @@
+echo|set /p="123" > test.txt