simulator: Add energy modelling subsystem to OpenDC

This pull request adds a subsystem to OpenDC for modelling power components in datacenters, 
such as UPSes, PDUs and PSUs. 
These components also take into account electrical losses that occur in real-world scenarios.

- Add module for datacenter power components (UPS, PDU)
- Integrate power subsystem with compute subsystem (PSU)
- Model power loss in power components

**Breaking API Changes**

1. `SimBareMetalMachine.powerDraw` is replaced by `SimBareMetalMachine.psu.powerDraw`

8 files changed, 752 insertions, 0 deletions

diff --git a/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPdu.kt b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPdu.kt
new file mode 100644
index 00000000..11034a57
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPdu.kt
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.power
+
+import org.opendc.simulator.resources.*
+
+/**
+ * A model of a Power Distribution Unit (PDU).
+ *
+ * @param interpreter The underlying [SimResourceInterpreter] to drive the simulation under the hood.
+ * @param idlePower The idle power consumption of the PDU independent of the load on the PDU.
+ * @param lossCoefficient The coefficient for the power loss of the PDU proportional to the square load.
+ */
+public class SimPdu(
+    interpreter: SimResourceInterpreter,
+    private val idlePower: Double = 0.0,
+    private val lossCoefficient: Double = 0.0,
+) : SimPowerInlet() {
+    /**
+     * The [SimResourceDistributor] that distributes the electricity over the PDU outlets.
+     */
+    private val distributor = SimResourceDistributorMaxMin(interpreter)
+
+    /**
+     * Create a new PDU outlet.
+     */
+    public fun newOutlet(): Outlet = Outlet(distributor.newOutput())
+
+    override fun createConsumer(): SimResourceConsumer = object : SimResourceConsumer by distributor {
+        override fun onNext(ctx: SimResourceContext): SimResourceCommand {
+            return when (val cmd = distributor.onNext(ctx)) {
+                is SimResourceCommand.Consume -> {
+                    val duration = cmd.work / cmd.limit
+                    val loss = computePowerLoss(cmd.limit)
+                    val newLimit = cmd.limit + loss
+
+                    SimResourceCommand.Consume(duration * newLimit, newLimit, cmd.deadline)
+                }
+                is SimResourceCommand.Idle -> {
+                    val loss = computePowerLoss(0.0)
+                    if (loss > 0.0)
+                        SimResourceCommand.Consume(Double.POSITIVE_INFINITY, loss, cmd.deadline)
+                    else
+                        cmd
+                }
+                else -> cmd
+            }
+        }
+
+        override fun toString(): String = "SimPdu.Consumer"
+    }
+
+    override fun toString(): String = "SimPdu"
+
+    /**
+     * Compute the power loss that occurs in the PDU.
+     */
+    private fun computePowerLoss(load: Double): Double {
+        // See https://download.schneider-electric.com/files?p_Doc_Ref=SPD_NRAN-66CK3D_EN
+        return idlePower + lossCoefficient * (load * load)
+    }
+
+    /**
+     * A PDU outlet.
+     */
+    public class Outlet(private val provider: SimResourceProvider) : SimPowerOutlet(), AutoCloseable {
+        override fun onConnect(inlet: SimPowerInlet) {
+            provider.startConsumer(inlet.createConsumer())
+        }
+
+        override fun onDisconnect(inlet: SimPowerInlet) {
+            provider.cancel()
+        }
+
+        /**
+         * Remove the outlet from the PDU.
+         */
+        override fun close() {
+            provider.close()
+        }
+
+        override fun toString(): String = "SimPdu.Outlet"
+    }
+}
diff --git a/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerInlet.kt b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerInlet.kt
new file mode 100644
index 00000000..0ac1f199
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerInlet.kt
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.power
+
+import org.opendc.simulator.resources.SimResourceConsumer
+
+/**
+ * An abstract inlet that consumes electricity from a power outlet.
+ */
+public abstract class SimPowerInlet {
+    /**
+     * A flag to indicate that the inlet is currently connected to an outlet.
+     */
+    public val isConnected: Boolean
+        get() = _outlet != null
+
+    /**
+     * The [SimPowerOutlet] to which the inlet is connected.
+     */
+    public val outlet: SimPowerOutlet?
+        get() = _outlet
+    internal var _outlet: SimPowerOutlet? = null
+
+    /**
+     * Create a [SimResourceConsumer] which represents the consumption of electricity from the power outlet.
+     */
+    public abstract fun createConsumer(): SimResourceConsumer
+}
diff --git a/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerOutlet.kt b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerOutlet.kt
new file mode 100644
index 00000000..72f52acc
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerOutlet.kt
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.power
+
+/**
+ * An abstract outlet that provides a source of electricity for datacenter components.
+ */
+public abstract class SimPowerOutlet {
+    /**
+     * A flag to indicate that the inlet is currently connected to an outlet.
+     */
+    public val isConnected: Boolean
+        get() = _inlet != null
+
+    /**
+     * The inlet that is connected to this outlet currently.
+     */
+    public val inlet: SimPowerInlet?
+        get() = _inlet
+    private var _inlet: SimPowerInlet? = null
+
+    /**
+     * Connect the specified power [inlet] to this outlet.
+     *
+     * @param inlet The inlet to connect to the outlet.
+     */
+    public fun connect(inlet: SimPowerInlet) {
+        check(!isConnected) { "Outlet already connected" }
+        check(!inlet.isConnected) { "Inlet already connected" }
+
+        _inlet = inlet
+        inlet._outlet = this
+
+        onConnect(inlet)
+    }
+
+    /**
+     * Disconnect the connected power outlet from this inlet
+     */
+    public fun disconnect() {
+        val inlet = _inlet
+        if (inlet != null) {
+            _inlet = null
+            assert(inlet._outlet == this) { "Inlet state incorrect" }
+            inlet._outlet = null
+
+            onDisconnect(inlet)
+        }
+    }
+
+    /**
+     * This method is invoked when an inlet is connected to the outlet.
+     */
+    protected abstract fun onConnect(inlet: SimPowerInlet)
+
+    /**
+     * This method is invoked when an inlet is disconnected from the outlet.
+     */
+    protected abstract fun onDisconnect(inlet: SimPowerInlet)
+}
diff --git a/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerSource.kt b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerSource.kt
new file mode 100644
index 00000000..3ef8ccc6
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPowerSource.kt
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.power
+
+import org.opendc.simulator.resources.SimResourceInterpreter
+import org.opendc.simulator.resources.SimResourceSource
+
+/**
+ * A [SimPowerOutlet] that represents a source of electricity.
+ *
+ * @param interpreter The underlying [SimResourceInterpreter] to drive the simulation under the hood.
+ */
+public class SimPowerSource(interpreter: SimResourceInterpreter, public val capacity: Double) : SimPowerOutlet() {
+    /**
+     * The resource source that drives this power source.
+     */
+    private val source = SimResourceSource(capacity, interpreter)
+
+    /**
+     * The power draw at this instant.
+     */
+    public val powerDraw: Double
+        get() = source.speed
+
+    override fun onConnect(inlet: SimPowerInlet) {
+        source.startConsumer(inlet.createConsumer())
+    }
+
+    override fun onDisconnect(inlet: SimPowerInlet) {
+        source.cancel()
+    }
+
+    override fun toString(): String = "SimPowerSource"
+}
diff --git a/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimUps.kt b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimUps.kt
new file mode 100644
index 00000000..f9431d21
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimUps.kt
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.power
+
+import org.opendc.simulator.resources.*
+
+/**
+ * A model of an Uninterruptible Power Supply (UPS).
+ *
+ * This model aggregates multiple power sources into a single source in order to ensure that power is always available.
+ *
+ * @param interpreter The underlying [SimResourceInterpreter] to drive the simulation under the hood.
+ * @param idlePower The idle power consumption of the UPS independent of the load.
+ * @param lossCoefficient The coefficient for the power loss of the UPS proportional to the load.
+ */
+public class SimUps(
+    interpreter: SimResourceInterpreter,
+    private val idlePower: Double = 0.0,
+    private val lossCoefficient: Double = 0.0,
+) : SimPowerOutlet() {
+    /**
+     * The resource aggregator used to combine the input sources.
+     */
+    private val aggregator = SimResourceAggregatorMaxMin(interpreter)
+
+    /**
+     * Create a new UPS outlet.
+     */
+    public fun newInlet(): SimPowerInlet {
+        val forward = SimResourceForwarder(isCoupled = true)
+        aggregator.addInput(forward)
+        return Inlet(forward)
+    }
+
+    override fun onConnect(inlet: SimPowerInlet) {
+        val consumer = inlet.createConsumer()
+        aggregator.startConsumer(object : SimResourceConsumer by consumer {
+            override fun onNext(ctx: SimResourceContext): SimResourceCommand {
+                return when (val cmd = consumer.onNext(ctx)) {
+                    is SimResourceCommand.Consume -> {
+                        val duration = cmd.work / cmd.limit
+                        val loss = computePowerLoss(cmd.limit)
+                        val newLimit = cmd.limit + loss
+
+                        SimResourceCommand.Consume(duration * newLimit, newLimit, cmd.deadline)
+                    }
+                    is SimResourceCommand.Idle -> {
+                        val loss = computePowerLoss(0.0)
+                        if (loss > 0.0)
+                            SimResourceCommand.Consume(Double.POSITIVE_INFINITY, loss, cmd.deadline)
+                        else
+                            cmd
+                    }
+                    else -> cmd
+                }
+            }
+        })
+    }
+
+    override fun onDisconnect(inlet: SimPowerInlet) {
+        aggregator.cancel()
+    }
+
+    /**
+     * Compute the power loss that occurs in the UPS.
+     */
+    private fun computePowerLoss(load: Double): Double {
+        // See https://download.schneider-electric.com/files?p_Doc_Ref=SPD_NRAN-66CK3D_EN
+        return idlePower + lossCoefficient * load
+    }
+
+    /**
+     * A UPS inlet.
+     */
+    public inner class Inlet(private val forwarder: SimResourceTransformer) : SimPowerInlet(), AutoCloseable {
+        override fun createConsumer(): SimResourceConsumer = forwarder
+
+        /**
+         * Remove the inlet from the PSU.
+         */
+        override fun close() {
+            forwarder.close()
+        }
+
+        override fun toString(): String = "SimPsu.Inlet"
+    }
+}
diff --git a/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPduTest.kt b/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPduTest.kt
new file mode 100644
index 00000000..17a174b7
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPduTest.kt
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.power
+
+import io.mockk.spyk
+import io.mockk.verify
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import org.opendc.simulator.core.runBlockingSimulation
+import org.opendc.simulator.resources.SimResourceConsumer
+import org.opendc.simulator.resources.SimResourceEvent
+import org.opendc.simulator.resources.SimResourceInterpreter
+import org.opendc.simulator.resources.consumer.SimWorkConsumer
+
+/**
+ * Test suite for the [SimPdu] class.
+ */
+internal class SimPduTest {
+    @Test
+    fun testZeroOutlets() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val pdu = SimPdu(interpreter)
+        source.connect(pdu)
+
+        assertEquals(0.0, source.powerDraw)
+    }
+
+    @Test
+    fun testSingleOutlet() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val pdu = SimPdu(interpreter)
+        source.connect(pdu)
+        pdu.newOutlet().connect(SimpleInlet())
+
+        assertEquals(50.0, source.powerDraw)
+    }
+
+    @Test
+    fun testDoubleOutlet() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val pdu = SimPdu(interpreter)
+        source.connect(pdu)
+
+        pdu.newOutlet().connect(SimpleInlet())
+        pdu.newOutlet().connect(SimpleInlet())
+
+        assertEquals(100.0, source.powerDraw)
+    }
+
+    @Test
+    fun testDisconnect() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val pdu = SimPdu(interpreter)
+        source.connect(pdu)
+        val consumer = spyk(SimWorkConsumer(100.0, utilization = 1.0))
+        val inlet = object : SimPowerInlet() {
+            override fun createConsumer(): SimResourceConsumer = consumer
+        }
+
+        val outlet = pdu.newOutlet()
+        outlet.connect(inlet)
+        outlet.disconnect()
+
+        verify { consumer.onEvent(any(), SimResourceEvent.Exit) }
+    }
+
+    @Test
+    fun testLoss() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        // https://download.schneider-electric.com/files?p_Doc_Ref=SPD_NRAN-66CK3D_EN
+        val pdu = SimPdu(interpreter, idlePower = 1.5, lossCoefficient = 0.015)
+        source.connect(pdu)
+        pdu.newOutlet().connect(SimpleInlet())
+        assertEquals(89.0, source.powerDraw, 0.01)
+    }
+
+    @Test
+    fun testOutletClose() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val pdu = SimPdu(interpreter)
+        source.connect(pdu)
+        val outlet = pdu.newOutlet()
+        outlet.close()
+
+        assertThrows<IllegalStateException> {
+            outlet.connect(SimpleInlet())
+        }
+    }
+
+    class SimpleInlet : SimPowerInlet() {
+        override fun createConsumer(): SimResourceConsumer = SimWorkConsumer(100.0, utilization = 0.5)
+    }
+}
diff --git a/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPowerSourceTest.kt b/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPowerSourceTest.kt
new file mode 100644
index 00000000..f3829ba1
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPowerSourceTest.kt
@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.power
+
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.spyk
+import io.mockk.verify
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertDoesNotThrow
+import org.junit.jupiter.api.assertThrows
+import org.opendc.simulator.core.runBlockingSimulation
+import org.opendc.simulator.resources.SimResourceConsumer
+import org.opendc.simulator.resources.SimResourceEvent
+import org.opendc.simulator.resources.SimResourceInterpreter
+import org.opendc.simulator.resources.consumer.SimWorkConsumer
+
+/**
+ * Test suite for the [SimPowerSource]
+ */
+internal class SimPowerSourceTest {
+    @Test
+    fun testInitialState() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+
+        assertFalse(source.isConnected)
+        assertNull(source.inlet)
+        assertEquals(100.0, source.capacity)
+    }
+
+    @Test
+    fun testDisconnectIdempotent() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+
+        assertDoesNotThrow { source.disconnect() }
+        assertFalse(source.isConnected)
+    }
+
+    @Test
+    fun testConnect() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val inlet = SimpleInlet()
+
+        source.connect(inlet)
+
+        assertTrue(source.isConnected)
+        assertEquals(inlet, source.inlet)
+        assertTrue(inlet.isConnected)
+        assertEquals(source, inlet.outlet)
+        assertEquals(100.0, source.powerDraw)
+    }
+
+    @Test
+    fun testDisconnect() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val consumer = spyk(SimWorkConsumer(100.0, utilization = 1.0))
+        val inlet = object : SimPowerInlet() {
+            override fun createConsumer(): SimResourceConsumer = consumer
+        }
+
+        source.connect(inlet)
+        source.disconnect()
+
+        verify { consumer.onEvent(any(), SimResourceEvent.Exit) }
+    }
+
+    @Test
+    fun testDisconnectAssertion() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val inlet = mockk<SimPowerInlet>(relaxUnitFun = true)
+        every { inlet.isConnected } returns false
+        every { inlet._outlet } returns null
+        every { inlet.createConsumer() } returns SimWorkConsumer(100.0, utilization = 1.0)
+
+        source.connect(inlet)
+
+        assertThrows<AssertionError> {
+            source.disconnect()
+        }
+    }
+
+    @Test
+    fun testOutletAlreadyConnected() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val inlet = SimpleInlet()
+
+        source.connect(inlet)
+        assertThrows<IllegalStateException> {
+            source.connect(SimpleInlet())
+        }
+
+        assertEquals(inlet, source.inlet)
+    }
+
+    @Test
+    fun testInletAlreadyConnected() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val inlet = mockk<SimPowerInlet>(relaxUnitFun = true)
+        every { inlet.isConnected } returns true
+
+        assertThrows<IllegalStateException> {
+            source.connect(inlet)
+        }
+    }
+
+    class SimpleInlet : SimPowerInlet() {
+        override fun createConsumer(): SimResourceConsumer = SimWorkConsumer(100.0, utilization = 1.0)
+    }
+}
diff --git a/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimUpsTest.kt b/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimUpsTest.kt
new file mode 100644
index 00000000..8d5fa857
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimUpsTest.kt
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.power
+
+import io.mockk.spyk
+import io.mockk.verify
+import org.junit.jupiter.api.Assertions.assertAll
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import org.opendc.simulator.core.runBlockingSimulation
+import org.opendc.simulator.resources.SimResourceConsumer
+import org.opendc.simulator.resources.SimResourceEvent
+import org.opendc.simulator.resources.SimResourceInterpreter
+import org.opendc.simulator.resources.consumer.SimWorkConsumer
+
+/**
+ * Test suite for the [SimUps] class.
+ */
+internal class SimUpsTest {
+    @Test
+    fun testSingleInlet() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        val ups = SimUps(interpreter)
+        source.connect(ups.newInlet())
+        ups.connect(SimpleInlet())
+
+        assertEquals(50.0, source.powerDraw)
+    }
+
+    @Test
+    fun testDoubleInlet() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source1 = SimPowerSource(interpreter, capacity = 100.0)
+        val source2 = SimPowerSource(interpreter, capacity = 100.0)
+        val ups = SimUps(interpreter)
+        source1.connect(ups.newInlet())
+        source2.connect(ups.newInlet())
+
+        ups.connect(SimpleInlet())
+
+        assertAll(
+            { assertEquals(50.0, source1.powerDraw) },
+            { assertEquals(50.0, source2.powerDraw) }
+        )
+    }
+
+    @Test
+    fun testLoss() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        // https://download.schneider-electric.com/files?p_Doc_Ref=SPD_NRAN-66CK3D_EN
+        val ups = SimUps(interpreter, idlePower = 4.0, lossCoefficient = 0.05)
+        source.connect(ups.newInlet())
+        ups.connect(SimpleInlet())
+
+        assertEquals(56.5, source.powerDraw)
+    }
+
+    @Test
+    fun testDisconnect() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source1 = SimPowerSource(interpreter, capacity = 100.0)
+        val source2 = SimPowerSource(interpreter, capacity = 100.0)
+        val ups = SimUps(interpreter)
+        source1.connect(ups.newInlet())
+        source2.connect(ups.newInlet())
+        val consumer = spyk(SimWorkConsumer(100.0, utilization = 1.0))
+        val inlet = object : SimPowerInlet() {
+            override fun createConsumer(): SimResourceConsumer = consumer
+        }
+
+        ups.connect(inlet)
+        ups.disconnect()
+
+        verify { consumer.onEvent(any(), SimResourceEvent.Exit) }
+    }
+
+    class SimpleInlet : SimPowerInlet() {
+        override fun createConsumer(): SimResourceConsumer = SimWorkConsumer(100.0, utilization = 0.5)
+    }
+}