Added Unit-Test for extensions using an older API

test/groovy/PiperStageWrapperTest.groovy

@@ -115,5 +115,33 @@ class PiperStageWrapperTest extends BasePiperTest {
         assertThat(loggingRule.log, containsString('Config: ['))
         assertThat(loggingRule.log, containsString('testBranch'))
     }
-}
 
+    @Test
+    void testStageOldInterceptor() {
+        helper.registerAllowedMethod('fileExists', [String.class], { path ->
+            return (path == '.pipeline/extensions/test_old_extension.groovy')
+        })
+
+        helper.registerAllowedMethod('load', [String.class], {
+            return helper.loadScript('test/resources/stages/test_old_extension.groovy')
+        })
+        nullScript.commonPipelineEnvironment.gitBranch = 'testBranch'
+
+        def executed = false
+        stepRule.step.piperStageWrapper(
+            script: nullScript,
+            juStabUtils: utils,
+            ordinal: 10,
+            stageName: 'test_old_extension'
+        ) {
+            executed = true
+        }
+
+        assertThat(executed, is(true))
+        assertThat(loggingRule.log, containsString('[piperStageWrapper] Running project interceptor \'.pipeline/extensions/test_old_extension.groovy\' for test_old_extension.'))
+        assertThat(loggingRule.log, containsString('[Warning] The interface to implement extensions has changed.'))
+        assertThat(loggingRule.log, containsString('Stage Name: test_old_extension'))
+        assertThat(loggingRule.log, containsString('Config: ['))
+        assertThat(loggingRule.log, containsString('testBranch'))
+    }
+}

test/resources/stages/test_old_extension.groovy

@@ -0,0 +1,7 @@
+void call(Closure originalStage, String stageName, Map configuration, Map params) {
+    echo "Stage Name: $stageName"
+    echo "Config: $configuration"
+    originalStage()
+    echo "Branch: ${params.script.commonPipelineEnvironment.gitBranch}"
+}
+return this