Add installDir project property detection

src/main/groovy/io/openliberty/tools/gradle/Liberty.groovy

@@ -169,27 +169,28 @@ class Liberty implements Plugin<Project> {
     }
 
     private static File getInstallDir(Project project) {
-        if (project.liberty.installDir == null) {
-           if (project.liberty.baseDir == null) {
-               return new File(project.buildDir, 'wlp')
-           } else {
-               return new File(project.liberty.baseDir, 'wlp')
-           }
+        if (project.hasProperty('liberty.installDir')) {
+            File installDir = checkAndAppendWlp(project, new File(project.projectDir, project.getProperties().get('liberty.installDir')))
+            project.getLogger().info("installDir project property detected. Using ${installDir.getCanonicalPath()}.")
+            return installDir
+        } else if (project.liberty.installDir == null) {
+            if (project.liberty.baseDir == null) {
+                return new File(project.buildDir, 'wlp')
+            } else {
+                return new File(project.liberty.baseDir, 'wlp')
+            }
         } else { // installDir is specified
-            String installDirPath = checkAndAppendWlp(project)
-            File installDir = new File(installDirPath)
-
-            return installDir;
+            return checkAndAppendWlp(project, new File(project.liberty.installDir));
         }
     }
 
-    private static String checkAndAppendWlp(Project project) {
-        String installDir = project.liberty.installDir
-        if (installDir.endsWith("wlp")) {
+    private static File checkAndAppendWlp(Project project, File installDir) {        
+        if (installDir.toString().endsWith("wlp")) {
             return installDir
         } else { // not valid wlp dir
             project.getLogger().warn(MessageFormat.format("The installDir {0} path does not reference a wlp folder. Using path {0}/wlp instead.", installDir))
-            return new File(installDir, 'wlp').toString()
+            return new File(installDir, 'wlp')
         }
     }
+
 }

src/test/groovy/io/openliberty/tools/gradle/InstallLiberty_installDir_missing_wlp_Test.groovy

@@ -26,6 +26,8 @@ class InstallLiberty_installDir_missing_wlp_Test extends AbstractIntegrationTest
     static File resourceDir = new File("build/resources/test/install-dir-property-test/installDir-missing-wlp")
 
     static File buildDir = new File(integTestDir, "/InstallLiberty_installDir_missing_wlp")
+    static String expectedPropertyDir = new File(buildDir, 'installDir-valid-install/build/wlp').getCanonicalPath()
+
     static String buildFilename = "build.gradle"
 
     @BeforeClass
@@ -45,4 +47,29 @@ class InstallLiberty_installDir_missing_wlp_Test extends AbstractIntegrationTest
         String output = result.getOutput()
         assert output.contains("path does not reference a wlp folder") : "Expected warning about installDir path not containing wlp"
     }
+
+    @Test
+    void test_installLiberty_installDir_cli_property_wlp() {
+        BuildResult result = GradleRunner.create()
+            .withProjectDir(buildDir)
+            .forwardOutput()
+            .withArguments('installLiberty', '-Pliberty.installDir=installDir-valid-install/build/wlp', '-i', '-s')
+            .build()
+
+        String output = result.getOutput()
+        assert output.contains("installDir project property detected. Using $expectedPropertyDir")
+    }
+
+    @Test
+    void test_installLiberty_installDir_cli_property() {
+        BuildResult result = GradleRunner.create()
+            .withProjectDir(buildDir)
+            .forwardOutput()
+            .withArguments('installLiberty', '-Pliberty.installDir=installDir-valid-install/build', '-i', '-s')
+            .build()
+
+        String output = result.getOutput()
+        assert output.contains("installDir project property detected. Using $expectedPropertyDir".drop(4))
+        assert output.contains("Using path $expectedPropertyDir instead.")
+    }
 }