Fix three ECCO power-bond bugs and add regression tests

src/cosim/algorithm/ecco_algorithm.cpp

@@ -309,6 +309,10 @@ class ecco_algorithm::impl
 
     void add_power_bond(cosim::variable_id input_a, cosim::variable_id output_a, cosim::variable_id input_b, cosim::variable_id output_b)
     {
+        simulators_.at(input_a.simulator).sim->expose_for_getting(input_a.type, input_a.reference);
+        simulators_.at(output_a.simulator).sim->expose_for_getting(output_a.type, output_a.reference);
+        simulators_.at(input_b.simulator).sim->expose_for_getting(input_b.type, input_b.reference);
+        simulators_.at(output_b.simulator).sim->expose_for_getting(output_b.type, output_b.reference);
         energies_.emplace_back();
         energies_.emplace_back();
         inputVariables_.push_back(input_a);

src/cosim/osp_config_parser.cpp

@@ -891,17 +891,20 @@ void add_power_bonds(const std::vector<osp_config_parser::PowerBondConnection>&
         }
 
         systemStructure.add_power_bond(pbName, powerbond);
+    }
 
-        // Check that the number of unique power bond names is equal to the number of power bonds. Otherwise, it is not possible to correctly connect the bonds.
-        std::sort(powerBondNames.begin(), powerBondNames.end());
-        auto uniqueCount = static_cast<int>(std::unique(powerBondNames.begin(), powerBondNames.end()) - powerBondNames.begin());
-        auto numPowerBonds = static_cast<int>(systemStructure.get_power_bonds().size());
+    // Check that the number of unique power bond names is equal to the number of
+    // power bonds. This must be verified after all bonds have been added; checking
+    // inside the loop would compare a partial count against the full unique-name
+    // count and spuriously throw when more than one bond is configured.
+    std::sort(powerBondNames.begin(), powerBondNames.end());
+    auto uniqueCount = static_cast<int>(std::unique(powerBondNames.begin(), powerBondNames.end()) - powerBondNames.begin());
+    auto numPowerBonds = static_cast<int>(systemStructure.get_power_bonds().size());
 
-        if (uniqueCount != numPowerBonds) {
-            std::ostringstream oss;
-            oss << "The number of powerbonds (" << numPowerBonds << ") is not equal to the number of unique power bond names (" << uniqueCount << ") found in the configured system. Power bond names must be unique pr. bond, that is found on only and exactly the two VariableConnections that form the bond.";
-            throw std::runtime_error(oss.str());
-        }
+    if (uniqueCount != numPowerBonds) {
+        std::ostringstream oss;
+        oss << "The number of powerbonds (" << numPowerBonds << ") is not equal to the number of unique power bond names (" << uniqueCount << ") found in the configured system. Power bond names must be unique pr. bond, that is found on only and exactly the two VariableConnections that form the bond.";
+        throw std::runtime_error(oss.str());
     }
 }
 

tests/CMakeLists.txt

@@ -1,7 +1,9 @@
 set(tests        
     "ecco_algorithm_from_system_structure_test"
-    "ecco_algorithm_multi_bond_test"    
+    "ecco_algorithm_multi_bond_test"
+    "ecco_algorithm_powerbond_logconfig_test"
     "ecco_algorithm_test"
+    "ecco_algorithm_two_bond_test"
     "file_observer_dynamic_logging_test"
     "file_observer_logging_test"
     "file_observer_logging_from_config_test"

tests/data/fmi2/quarter_truck/OspSystemStructure_MultiBond.xml

@@ -0,0 +1,97 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  Two independent chassis+wheel pairs, each connected by a separate power bond.
+  Used by ecco_algorithm_two_bond_test to exercise the multi-bond code path.
+
+  Before the fix in add_power_bonds() (osp_config_parser.cpp), load_osp_config()
+  would throw "1 != 2" on this file because the uniqueCount validation was placed
+  inside the per-bond loop and fired after the first bond was added.
+-->
+<OspSystemStructure xmlns="http://opensimulationplatform.com/MSMI/OSPSystemStructure" version="0.1">
+    <BaseStepSize>0.0001</BaseStepSize>
+    <Algorithm>ecco</Algorithm>
+    <Simulators>
+        <Simulator name="chassis1" source="Chassis.fmu">
+            <InitialValues>
+                <InitialValue variable="mass">
+                    <Real value="400"/>
+                </InitialValue>
+                <InitialValue variable="solverType">
+                    <String value="Euler"/>
+                </InitialValue>
+                <InitialValue variable="timeStep">
+                    <Real value="1e-5"/>
+                </InitialValue>
+            </InitialValues>
+        </Simulator>
+        <Simulator name="wheel1" source="Wheel.fmu">
+            <InitialValues>
+                <InitialValue variable="mass">
+                    <Real value="40"/>
+                </InitialValue>
+                <InitialValue variable="solverType">
+                    <String value="Euler"/>
+                </InitialValue>
+                <InitialValue variable="timeStep">
+                    <Real value="1e-5"/>
+                </InitialValue>
+            </InitialValues>
+        </Simulator>
+        <Simulator name="chassis2" source="Chassis.fmu">
+            <InitialValues>
+                <InitialValue variable="mass">
+                    <Real value="400"/>
+                </InitialValue>
+                <InitialValue variable="solverType">
+                    <String value="Euler"/>
+                </InitialValue>
+                <InitialValue variable="timeStep">
+                    <Real value="1e-5"/>
+                </InitialValue>
+            </InitialValues>
+        </Simulator>
+        <Simulator name="wheel2" source="Wheel.fmu">
+            <InitialValues>
+                <InitialValue variable="mass">
+                    <Real value="40"/>
+                </InitialValue>
+                <InitialValue variable="solverType">
+                    <String value="Euler"/>
+                </InitialValue>
+                <InitialValue variable="timeStep">
+                    <Real value="1e-5"/>
+                </InitialValue>
+            </InitialValues>
+        </Simulator>
+    </Simulators>
+    <Connections>
+        <VariableConnection powerBond="bond1">
+            <Variable simulator="chassis1" name="velocity" causality="input"/>
+            <Variable simulator="wheel1" name="in_vel" causality="output"/>
+        </VariableConnection>
+        <VariableConnection powerBond="bond1">
+            <Variable simulator="wheel1" name="out_spring_damper_f" causality="input"/>
+            <Variable simulator="chassis1" name="force" causality="output"/>
+        </VariableConnection>
+        <VariableConnection powerBond="bond2">
+            <Variable simulator="chassis2" name="velocity" causality="input"/>
+            <Variable simulator="wheel2" name="in_vel" causality="output"/>
+        </VariableConnection>
+        <VariableConnection powerBond="bond2">
+            <Variable simulator="wheel2" name="out_spring_damper_f" causality="input"/>
+            <Variable simulator="chassis2" name="force" causality="output"/>
+        </VariableConnection>
+    </Connections>
+    <EccoConfiguration>
+        <SafetyFactor>0.99</SafetyFactor>
+        <StepSize>0.0001</StepSize>
+        <MinimumStepSize>0.00001</MinimumStepSize>
+        <MaximumStepSize>0.01</MaximumStepSize>
+        <MinimumChangeRate>0.2</MinimumChangeRate>
+        <MaximumChangeRate>1.5</MaximumChangeRate>
+        <ProportionalGain>0.2</ProportionalGain>
+        <IntegralGain>0.15</IntegralGain>
+        <RelativeTolerance>1e-6</RelativeTolerance>
+        <AbsoluteTolerance>1e-6</AbsoluteTolerance>
+    </EccoConfiguration>
+</OspSystemStructure>

tests/ecco_algorithm_multi_bond_test.cpp

@@ -58,11 +58,15 @@ int main()
         auto chassisIndex = entityMaps.simulators.at("chassis");
         auto wheelIndex = entityMaps.simulators.at("wheel");
 
-        auto chassisForce = cosim::variable_id{chassisIndex, cosim::variable_type::real, 19};
-        auto chassisVel = cosim::variable_id{chassisIndex, cosim::variable_type::real, 22};
-        auto wheelCForce = cosim::variable_id{wheelIndex, cosim::variable_type::real, 26};
-        auto wheelCVel = cosim::variable_id{wheelIndex, cosim::variable_type::real, 24};
-        ecco_algo->add_power_bond(chassisVel, chassisForce, wheelCForce, wheelCVel); // chassis -> wheel (chassis port)
+        // Correct refs from FMU model descriptions:
+        //   Chassis: velocity (FMU output) = ref 23, force (FMU input) = ref 4
+        //   Wheel:   out_spring_damper_f (FMU output) = ref 15, in_vel (FMU input) = ref 7
+        // inject_system_structure already registered the power bond from OspSystemStructure.xml;
+        // do NOT call add_power_bond again here.
+        auto chassisVel = cosim::variable_id{chassisIndex, cosim::variable_type::real, 23};
+        auto chassisForce = cosim::variable_id{chassisIndex, cosim::variable_type::real, 4};
+        auto wheelOutForce = cosim::variable_id{wheelIndex, cosim::variable_type::real, 15};
+        auto wheelInVel = cosim::variable_id{wheelIndex, cosim::variable_type::real, 7};
 
         auto file_obs = std::make_unique<cosim::file_observer>("./logDir", logXmlPath);
         execution.add_observer(std::move(file_obs));
@@ -71,9 +75,9 @@ int main()
         auto t_observer = std::make_shared<cosim::time_series_observer>(50000);
         execution.add_observer(t_observer);
         t_observer->start_observing(chassisVel);
-        t_observer->start_observing(wheelCVel);
+        t_observer->start_observing(wheelInVel);
         t_observer->start_observing(chassisForce);
-        t_observer->start_observing(wheelCForce);
+        t_observer->start_observing(wheelOutForce);
 
         auto csv_observer = std::make_shared<cosim::file_observer>(".");
         execution.add_observer(csv_observer);
@@ -86,9 +90,7 @@ int main()
         t_observer->get_step_numbers(chassisVel.simulator, startTime, midTime, gsl::make_span(stepNums, 2));
         const auto numSamples = stepNums[1] - stepNums[0];
         std::vector<double> chassisVels(numSamples);
-        std::vector<double> wheelCVels(numSamples);
-        std::vector<double> wheelGVels(numSamples);
-        std::vector<double> groundVels(numSamples);
+        std::vector<double> wheelInVels(numSamples);
         std::vector<cosim::step_number> steps(numSamples);
         std::vector<cosim::time_point> timeValues(numSamples);
 
@@ -100,22 +102,20 @@ int main()
             gsl::make_span(steps),
             gsl::make_span(timeValues));
         t_observer->get_real_samples(
-            wheelCVel.simulator,
-            wheelCVel.reference,
+            wheelInVel.simulator,
+            wheelInVel.reference,
             0,
-            gsl::make_span(wheelCVels),
+            gsl::make_span(wheelInVels),
             gsl::make_span(steps),
             gsl::make_span(timeValues));
 
-        std::cout << "time,step #,stepsize,chassisVel,wheelCVel,wheelGVel,groundVel" << std::endl;
+        std::cout << "time,step #,stepsize,chassisVel,wheelInVel" << std::endl;
         for (int i = 1; i < numSamples; ++i) {
             std::cout << cosim::to_double_time_point(timeValues[i])
                       << "," << steps[i]
                       << "," << cosim::to_double_duration(timeValues[i] - timeValues[i - 1], timeValues[i - 1])
                       << "," << chassisVels[i]
-                      << "," << wheelCVels[i]
-                      << "," << wheelGVels[i]
-                      << "," << groundVels[i]
+                      << "," << wheelInVels[i]
                       << std::endl;
         }
     } catch (const std::exception& e) {

tests/ecco_algorithm_powerbond_logconfig_test.cpp

@@ -0,0 +1,83 @@
+/**
+ * Regression test for: crash "Variable with reference N not found in exposed variables"
+ * when using the ECCO algorithm with a file_observer config that omits power bond input
+ * variables (force/in_vel) from the logged variable list.
+ *
+ * Root cause: ecco_algorithm::impl::add_power_bond stored all four bond variable IDs but
+ * never called expose_for_getting on them. adjust_step_size then called get_real() on all
+ * four variables, which throws for any variable not previously exposed for getting. The
+ * default file_observer (no config) accidentally hid the bug by exposing ALL variables;
+ * a config-restricted observer only exposes the listed variables, triggering the crash for
+ * FMU-input variables (force, in_vel) not present in the log config.
+ */
+
+#include <cosim/algorithm.hpp>
+#include <cosim/fs_portability.hpp>
+#include <cosim/log/simple.hpp>
+#include <cosim/observer/file_observer.hpp>
+#include <cosim/osp_config_parser.hpp>
+#include <cosim/time.hpp>
+
+#include <cstdlib>
+#include <exception>
+#include <memory>
+#include <stdexcept>
+
+
+#define REQUIRE(test) \
+    if (!(test)) throw std::runtime_error("Requirement not satisfied: " #test)
+
+int main()
+{
+    try {
+        const auto testDataDir = std::getenv("TEST_DATA_DIR");
+        REQUIRE(testDataDir);
+        cosim::log::setup_simple_console_logging();
+        cosim::log::set_global_output_level(cosim::log::info);
+
+        constexpr cosim::time_point endTime = cosim::to_time_point(0.1);
+
+        auto resolver = cosim::default_model_uri_resolver();
+        const auto configPath = cosim::filesystem::path(testDataDir) / "fmi2" / "quarter_truck" / "OspSystemStructure.xml";
+        const auto config = cosim::load_osp_config(configPath, *resolver);
+
+        auto ecco_params = std::get<cosim::ecco_algorithm_params>(config.algorithm_configuration);
+        auto ecco_algo = std::make_shared<cosim::ecco_algorithm>(ecco_params);
+
+        auto execution = cosim::execution(config.start_time, ecco_algo);
+
+        // inject_system_structure registers the power bond (chassis <-> wheel) by calling
+        // ecco_algorithm::add_power_bond internally.
+        const auto entityMaps = cosim::inject_system_structure(execution, config.system_structure, config.initial_values);
+        REQUIRE(entityMaps.simulators.size() == 2);
+
+        // Build a log config that intentionally omits the FMU-input bond variables:
+        //   chassis.force  (ref=4,  FMU input / bond "output_a")
+        //   wheel.in_vel   (ref=7,  FMU input / bond "output_b")
+        // Before the fix, adjust_step_size would call get_real() on these refs and throw
+        // "Variable with reference N not found in exposed variables" because no observer
+        // had called expose_for_getting on them.
+        cosim::file_observer_config log_config{};
+        log_config.set_timestamped_filenames(false);
+        // Log only output variables for chassis — force (ref=4) is deliberately absent.
+        log_config.log_simulator_variables("chassis", {"position", "velocity"});
+        // Log only output variables for wheel — in_vel (ref=7) is deliberately absent.
+        log_config.log_simulator_variables("wheel", {"position", "out_spring_damper_f", "velocity"});
+
+        auto file_obs = std::make_unique<cosim::file_observer>(
+            cosim::filesystem::current_path() / "powerbond_logconfig_logs",
+            log_config);
+        execution.add_observer(std::move(file_obs));
+
+        // This must complete without throwing. Before the fix it would crash with:
+        //   "Variable with reference N not found in exposed variables"
+        auto simResult = execution.simulate_until(endTime);
+        REQUIRE(simResult);
+
+    } catch (const std::exception& e) {
+        std::cerr << "Error: " << e.what() << std::endl;
+        return 1;
+    }
+
+    return 0;
+}

tests/ecco_algorithm_two_bond_test.cpp

@@ -0,0 +1,71 @@
+/**
+ * Regression test for: add_power_bonds() spuriously throws
+ * "The number of powerbonds (1) is not equal to the number of unique power bond
+ *  names (2)" when two bonds are configured.
+ *
+ * Root cause: the uniqueCount != numPowerBonds validation was placed inside the
+ * per-bond loop in add_power_bonds() (osp_config_parser.cpp). After the first
+ * bond is added, numPowerBonds == 1 but uniqueCount == 2 (computed up front from
+ * all connections), causing a spurious throw. The check must run after all bonds
+ * have been registered, i.e. outside the loop.
+ *
+ * This test uses two independent chassis+wheel pairs (OspSystemStructure_MultiBond.xml),
+ * each connected by a separate power bond. Before the fix, load_osp_config() throws
+ * on that file. After the fix it must load, simulate, and complete without error.
+ */
+
+#include <cosim/algorithm.hpp>
+#include <cosim/fs_portability.hpp>
+#include <cosim/log/simple.hpp>
+#include <cosim/osp_config_parser.hpp>
+#include <cosim/time.hpp>
+
+#include <cstdlib>
+#include <exception>
+#include <memory>
+#include <stdexcept>
+
+
+#define REQUIRE(test) \
+    if (!(test)) throw std::runtime_error("Requirement not satisfied: " #test)
+
+int main()
+{
+    try {
+        const auto testDataDir = std::getenv("TEST_DATA_DIR");
+        REQUIRE(testDataDir);
+        cosim::log::setup_simple_console_logging();
+        cosim::log::set_global_output_level(cosim::log::info);
+
+        constexpr cosim::time_point endTime = cosim::to_time_point(0.1);
+
+        auto resolver = cosim::default_model_uri_resolver();
+        const auto configPath = cosim::filesystem::path(testDataDir) / "fmi2" / "quarter_truck" / "OspSystemStructure_MultiBond.xml";
+
+        // Before the fix this throws:
+        //   "The number of powerbonds (1) is not equal to the number of unique
+        //    power bond names (2) ..."
+        // because the uniqueCount check fired inside the per-bond loop after
+        // only the first of the two bonds had been added.
+        const auto config = cosim::load_osp_config(configPath, *resolver);
+
+        auto ecco_params = std::get<cosim::ecco_algorithm_params>(config.algorithm_configuration);
+        auto ecco_algo = std::make_shared<cosim::ecco_algorithm>(ecco_params);
+
+        auto execution = cosim::execution(config.start_time, ecco_algo);
+
+        const auto entityMaps = cosim::inject_system_structure(
+            execution, config.system_structure, config.initial_values);
+
+        REQUIRE(entityMaps.simulators.size() == 4); // chassis1, wheel1, chassis2, wheel2
+
+        auto simResult = execution.simulate_until(endTime);
+        REQUIRE(simResult);
+
+    } catch (const std::exception& e) {
+        std::cerr << "Error: " << e.what() << std::endl;
+        return 1;
+    }
+
+    return 0;
+}