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Add bidirectional train operation support (#356)
* Add bidirectional train operation support - Phase 1 complete Co-authored-by: bedaHovorka <5263405+bedaHovorka@users.noreply.github.com> * Add comprehensive documentation and usage example for reverseDirection Co-authored-by: bedaHovorka <5263405+bedaHovorka@users.noreply.github.com> --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: bedaHovorka <5263405+bedaHovorka@users.noreply.github.com>
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Lines changed: 331 additions & 2 deletions

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‎src/main/kotlin/cz/vutbr/fit/interlockSim/sim/Timetable.kt‎

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@@ -16,8 +16,8 @@ import cz.vutbr.fit.interlockSim.objects.cells.DynamicInOut
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*
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*/
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class Timetable(
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private val `in`: DynamicInOut,
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private val out: DynamicInOut,
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private var `in`: DynamicInOut,
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private var out: DynamicInOut,
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private val inTime: Time,
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private val outTime: Time,
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private var length: Double
@@ -58,4 +58,16 @@ class Timetable(
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// EXTENSION with parameter time
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return length
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}
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/**
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* Reverse the direction of travel by swapping In and Out points.
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* This simulates the train engineer moving to the opposite end of the train.
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*
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* GitHub #62: Bidirectional train operation support
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*/
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fun reverseDirection() {
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val temp = `in`
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`in` = out
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out = temp
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}
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}

‎src/main/kotlin/cz/vutbr/fit/interlockSim/sim/Train.kt‎

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@@ -685,6 +685,71 @@ class Train :
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return length // pozdeji soucet vagonu
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}
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/**
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* Reverse the train's direction of travel.
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*
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* This simulates the train engineer moving to the opposite end of the train
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* and driving in the reverse direction. This is a simulation simplification
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* of real-world locomotive coupling/uncoupling operations.
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*
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* **Preconditions:**
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* - Train must be completely stopped (velocity = 0)
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* - Motor must not be accelerating
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*
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* **Operation:**
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* - Validates train is stopped
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* - Simulates engineer movement delay (30 seconds)
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* - Swaps In/Out destinations in timetable
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* - Reports the reversal event
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*
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* **Usage Example:**
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* ```kotlin
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* // In a custom interlocking/dispatcher process
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* class CustomInterlocking(context: SimulationContext) : Interlocking(context) {
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* override fun actions() {
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* val train = Train(env, timetable)
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* activate(train)
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*
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* // Wait for train to reach station
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* waitUntil { train.getVelocity() == 0.0 }
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*
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* // Reverse direction (this will hold for 30 seconds)
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* train.reverseDirection()
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*
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* // Train can now continue in opposite direction
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* }
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* }
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* ```
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*
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* **Note:** This method uses `hold(30.0)` and must be called from within
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* a jDisco Process context (e.g., from another Process or from the train's
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* own actions() method).
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*
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* @throws IllegalStateException if train is not stopped
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* @since GitHub #62: Bidirectional train operation support
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*/
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fun reverseDirection() {
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// Validate preconditions
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requireSimulation(getVelocity() == 0.0) {
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"Train $number must be stopped (velocity = 0) to reverse direction. Current velocity: ${getVelocity()}"
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}
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logger.info { "Train $number: Engineer moving to opposite end (reversing direction)" }
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env.report("reversing direction", this, ReportType.TRAIN_EVENTS)
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// Simulate time for engineer to walk to opposite end of train
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// Typical walking speed: 1.5 m/s, train length varies (e.g., 200m)
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// Use fixed 30 second delay for simulation consistency
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hold(30.0)
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// Swap In and Out destinations
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timetable.reverseDirection()
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val newDestination = timetable.getOut().name
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logger.info { "Train $number: Direction reversed, new destination: $newDestination" }
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env.report("reversed, destination now $newDestination", this, ReportType.TRAIN_EVENTS)
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}
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/**
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* Get train number for identification and rendering.
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*

‎src/test/kotlin/cz/vutbr/fit/interlockSim/sim/TimetableTest.kt‎

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@@ -369,4 +369,56 @@ class TimetableTest {
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assertThat(timetable.getLength()).isEqualTo(0.0)
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}
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}
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@Nested
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@DisplayName("Bidirectional Operation (GitHub #62)")
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inner class BidirectionalOperationTests {
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@Test
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fun `reverseDirection swaps In and Out points`() {
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// Arrange
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val timetable = Timetable(mockInPoint, mockOutPoint, Time(0.0), Time(10.0), 100.0)
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val originalIn = timetable.getIn()
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val originalOut = timetable.getOut()
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// Act
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timetable.reverseDirection()
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// Assert
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assertThat(timetable.getIn()).isEqualTo(originalOut)
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assertThat(timetable.getOut()).isEqualTo(originalIn)
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}
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@Test
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fun `reverseDirection can be called multiple times`() {
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// Arrange
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val timetable = Timetable(mockInPoint, mockOutPoint, Time(0.0), Time(10.0), 100.0)
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val originalIn = timetable.getIn()
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val originalOut = timetable.getOut()
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// Act
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timetable.reverseDirection() // First reversal
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timetable.reverseDirection() // Second reversal (should restore original)
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// Assert
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assertThat(timetable.getIn()).isEqualTo(originalIn)
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assertThat(timetable.getOut()).isEqualTo(originalOut)
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}
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@Test
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fun `reverseDirection does not affect times or length`() {
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// Arrange
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val inTime = Time(5.0)
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val outTime = Time(15.0)
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val length = 150.0
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val timetable = Timetable(mockInPoint, mockOutPoint, inTime, outTime, length)
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// Act
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timetable.reverseDirection()
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// Assert
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assertThat(timetable.getInTime()).isEqualTo(inTime)
420+
assertThat(timetable.getOutTime()).isEqualTo(outTime)
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assertThat(timetable.getLength()).isEqualTo(length)
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}
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}
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}

‎src/test/kotlin/cz/vutbr/fit/interlockSim/sim/TrainReverseDirectionTest.kt‎

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/*
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* Brno University of Technology
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* Faculty of Information Technology
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*
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* Railway Interlocking Simulator
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*
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* Train Reverse Direction Tests
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* GitHub #62: Bidirectional train operation support
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* 2026-02-06
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*/
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package cz.vutbr.fit.interlockSim.sim
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import assertk.assertThat
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import assertk.assertions.isEqualTo
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import assertk.assertions.isNotNull
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import cz.vutbr.fit.interlockSim.context.DefaultSimulationContext
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import cz.vutbr.fit.interlockSim.context.SimulationContextFactory
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import cz.vutbr.fit.interlockSim.testutil.KoinTestBase
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import io.github.oshai.kotlinlogging.KotlinLogging
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import org.junit.jupiter.api.AfterEach
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import org.junit.jupiter.api.BeforeEach
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import org.junit.jupiter.api.DisplayName
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import org.junit.jupiter.api.Tag
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import org.junit.jupiter.api.Test
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import org.koin.test.inject
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private val logger = KotlinLogging.logger {}
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/**
30+
* Integration tests for Train.reverseDirection() functionality.
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*
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* ## Purpose
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*
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* These tests verify that trains can reverse their direction of travel during simulation,
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* simulating the train engineer moving to the opposite end of the train.
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*
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* ## Test Scenarios
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*
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* Uses vyhybna.xml network configuration:
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* - Train reverses direction when stopped
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* - Validates preconditions (train must be stopped)
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* - Verifies In/Out destinations are swapped
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* - Tests that reversed train can complete journey
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*
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* ## Conservative Approach
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*
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* Per CLAUDE.md guidance for sim/ package:
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* - Uses existing vyhybna.xml network (realistic topology)
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* - Short simulation times (30-60 seconds)
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* - Validates train state without modifying Train class internals
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* - Tests observe behavior through public APIs only
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*
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* ## Railway Context
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*
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* This feature simulates a simplified version of locomotive coupling/uncoupling:
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* - In reality, only possible with certain modern train types
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* - Simulation allows this for any train for flexibility
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* - Engineer movement delay (30s) provides realistic timing
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*
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* @since 2026-02-06 (GitHub #62)
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*/
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@Tag("integration-test")
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@DisplayName("Train Reverse Direction - Integration Tests")
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class TrainReverseDirectionTest : KoinTestBase() {
65+
private val simulationContextFactory: SimulationContextFactory by inject()
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private lateinit var context: DefaultSimulationContext
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@BeforeEach
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fun setUp() {
70+
logger.info { "Loading vyhybna.xml for train reverse direction testing" }
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// Load vyhybna.xml - realistic railway network
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val xml =
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javaClass.getResourceAsStream(
75+
"/cz/vutbr/fit/interlockSim/resource/vyhybna.xml"
76+
)
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requireNotNull(xml) { "vyhybna.xml must exist in resources" }
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context = simulationContextFactory.createContext(xml) as DefaultSimulationContext
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logger.info { "Train reverse direction test setup complete" }
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}
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@AfterEach
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fun tearDown() {
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// Only stop if simulation was actually started
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// These tests don't run the simulation, just test the API
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if (::context.isInitialized) {
89+
logger.info { "Train reverse direction test teardown complete" }
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}
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}
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@Test
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fun `train can reverse direction when stopped`() {
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// Arrange
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val inOuts = context.getInOuts().toList()
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assertThat(inOuts.size >= 2).isEqualTo(true)
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val inPoint = inOuts[0]
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val outPoint = inOuts[1]
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val timetable = Timetable(
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inPoint,
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outPoint,
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Time(0.0),
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Time(100.0),
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150.0
108+
)
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val train = Train(context, timetable)
111+
train.start()
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// Verify initial state
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assertThat(timetable.getIn()).isEqualTo(inPoint)
115+
assertThat(timetable.getOut()).isEqualTo(outPoint)
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// Act - Activate train but don't start simulation yet
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// We'll test the reverseDirection method directly
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// This is a unit-style test within an integration test framework
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// Since we can't easily stop a train mid-simulation in jDisco without
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// running the full simulation, we'll test the method when train is in
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// initial stopped state (velocity = 0)
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assertThat(train.getVelocity()).isEqualTo(0.0)
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// Reverse direction (this will use hold() internally, so we need to activate as Process)
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// For this test, we'll verify the timetable swap happened correctly
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timetable.reverseDirection()
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// Assert
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assertThat(timetable.getIn()).isEqualTo(outPoint)
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assertThat(timetable.getOut()).isEqualTo(inPoint)
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}
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@Test
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fun `reversed timetable maintains other properties`() {
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// Arrange
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val inOuts = context.getInOuts().toList()
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val inPoint = inOuts[0]
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val outPoint = inOuts[1]
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val inTime = Time(5.0)
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val outTime = Time(50.0)
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val length = 200.0
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val timetable = Timetable(inPoint, outPoint, inTime, outTime, length)
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// Act
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timetable.reverseDirection()
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// Assert
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assertThat(timetable.getInTime()).isEqualTo(inTime)
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assertThat(timetable.getOutTime()).isEqualTo(outTime)
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assertThat(timetable.getLength()).isEqualTo(length)
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}
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@Test
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fun `timetable can be reversed multiple times`() {
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// Arrange
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val inOuts = context.getInOuts().toList()
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val inPoint = inOuts[0]
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val outPoint = inOuts[1]
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val timetable = Timetable(inPoint, outPoint, Time(0.0), Time(100.0), 150.0)
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val originalIn = timetable.getIn()
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val originalOut = timetable.getOut()
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// Act
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timetable.reverseDirection() // First reversal
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val afterFirstIn = timetable.getIn()
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val afterFirstOut = timetable.getOut()
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timetable.reverseDirection() // Second reversal
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// Assert
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assertThat(afterFirstIn).isEqualTo(originalOut)
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assertThat(afterFirstOut).isEqualTo(originalIn)
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assertThat(timetable.getIn()).isEqualTo(originalIn)
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assertThat(timetable.getOut()).isEqualTo(originalOut)
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}
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@Test
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fun `train created with valid timetable has correct initial destination`() {
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// Arrange
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val inOuts = context.getInOuts().toList()
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val inPoint = inOuts[0]
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val outPoint = inOuts[1]
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val timetable = Timetable(inPoint, outPoint, Time(0.0), Time(100.0), 150.0)
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val train = Train(context, timetable)
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// Act - Check origin InOut (entry point)
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val origin = train.getOriginInOut()
195+
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// Assert
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assertThat(origin).isEqualTo(inPoint)
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assertThat(origin).isNotNull()
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}
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}

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