Added support for beforeAgent property in when statements

src/main/groovy/com/lesfurets/jenkins/unit/declarative/WhenDeclaration.groovy

@@ -21,6 +21,7 @@ class WhenDeclaration extends GenericPipelineDeclaration {
     Closure<Boolean> expression
     String envName
     String envValue
+    Boolean beforeAgent
 
     def allOf(@DelegatesTo(strategy = DELEGATE_FIRST, value = AllOfDeclaration) Closure closure) {
         this.allOf = createComponent(AllOfDeclaration, closure)
@@ -66,6 +67,10 @@ class WhenDeclaration extends GenericPipelineDeclaration {
         }
     }
 
+    def beforeAgent (Boolean arg) {
+        this.beforeAgent = arg
+    }
+
     def buildingTag () {
         this.buildingTag = true
     }

src/test/groovy/com/lesfurets/jenkins/unit/declarative/TestDeclarativePipeline.groovy

@@ -419,6 +419,24 @@ class TestDeclarativePipeline extends DeclarativePipelineTest {
         assertJobStatusSuccess()
     }
 
+    @Test void when_nested_when_beforeAgent_with_matching_branch_expression() throws Exception {
+        addEnvVar('BRANCH_NAME', 'main')
+        runScript('Nested_BeforeAgent_Jenkinsfile')
+        printCallStack()
+        assertCallStack().contains('Executing nested when beforeAgent expression')
+        assertCallStack().contains('Executing on agent [label:beforeAgent-testLabel]')
+        assertJobStatusSuccess()
+    }
+
+    @Test void when_nested_when_beforeAgent_with_nonmatching_branch_expression() throws Exception {
+        addEnvVar('BRANCH_NAME', 'dev')
+        runScript('Nested_BeforeAgent_Jenkinsfile')
+        printCallStack()
+        assertCallStack().contains('Skipping stage Example nested when beforeAgent expression')
+        assertCallStack().doesNotContain('Executing on agent [label:beforeAgent-testLabel]')
+        assertJobStatusSuccess()
+    }
+
     @Test void when_branch_using_explicit_equals_comparator() throws Exception {
         addEnvVar('BRANCH_NAME', 'develop')
         runScript('Branch_Jenkinsfile')

src/test/jenkins/jenkinsfiles/Nested_BeforeAgent_Jenkinsfile

@@ -0,0 +1,22 @@
+pipeline {
+    agent any
+    stages {
+        stage('Example Build') {
+            steps {
+                echo 'Hello World'
+            }
+        }
+        stage('Example nested when beforeAgent expression') {
+            agent {
+                label "beforeAgent-testLabel"
+            }
+            when {
+                beforeAgent true
+                branch 'main'
+            }
+            steps {
+                echo 'Executing nested when beforeAgent expression'
+            }
+        }
+    }
+}