Made sure that Check() is called before doing much else in IsLinear() and added a case for catching undefined objectives in Check() + added tests for all of the above

Author: kwesiRutledge

mpiErrors/no_objective_defined.go

@@ -0,0 +1,7 @@
+package mpiErrors
+
+type NoObjectiveDefinedError struct{}
+
+func (e NoObjectiveDefinedError) Error() string {
+	return "No objective defined for the optimization problem; please define one with SetObjective()"
+}

problem/optimization_problem.go

@@ -3,6 +3,7 @@ package problem
 import (
 	"fmt"
 
+	"github.com/MatProGo-dev/MatProInterface.go/mpiErrors"
 	"github.com/MatProGo-dev/MatProInterface.go/optim"
 	"github.com/MatProGo-dev/SymbolicMath.go/symbolic"
 )
@@ -278,6 +279,10 @@ Description:
 */
 func (op *OptimizationProblem) Check() error {
 	// Check Objective
+	if op.Objective == (Objective{}) {
+		return mpiErrors.NoObjectiveDefinedError{}
+	}
+
 	err := op.Objective.Check()
 	if err != nil {
 		return fmt.Errorf("the objective is not valid: %v", err)
@@ -313,6 +318,13 @@ Description:
 	2. All constraints are linear (i.e., an affine combination of variables in an inequality or equality).
 */
 func (op *OptimizationProblem) IsLinear() bool {
+	// Input Processing
+	// Verify that the problem is well-formed
+	err := op.Check()
+	if err != nil {
+		panic(fmt.Errorf("the optimization problem is not well-formed: %v", err))
+	}
+
 	// Check Objective
 	if !op.Objective.IsLinear() {
 		return false

testing/problem/optimization_problem_test.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/MatProGo-dev/MatProInterface.go/mpiErrors"
 	"github.com/MatProGo-dev/MatProInterface.go/optim"
 	"github.com/MatProGo-dev/MatProInterface.go/problem"
 	"github.com/MatProGo-dev/SymbolicMath.go/symbolic"
@@ -1021,6 +1022,74 @@ func TestOptimizationProblem_Check2(t *testing.T) {
 	}
 }
 
+/*
+TestOptimizationProblem_Check3
+Description:
+
+	Tests the Check function with a simple problem
+	that has one variable and no objective defined.
+	The mpiErrors.NoObjectiveDefinedError should be created.
+*/
+func TestOptimizationProblem_Check3(t *testing.T) {
+	// Constants
+	p1 := problem.NewProblem("TestOptimizationProblem_Check3")
+	v1 := p1.AddVariable()
+
+	// Add variable to problem
+	p1.Variables = append(p1.Variables, v1)
+
+	// Algorithm
+	err := p1.Check()
+	if err == nil {
+		t.Errorf("expected an error; received nil")
+	} else {
+		expectedError := mpiErrors.NoObjectiveDefinedError{}
+		if err.Error() != expectedError.Error() {
+			t.Errorf("unexpected error: %v", err)
+		}
+	}
+}
+
+/*
+TestOptimizationProblem_Check4
+Description:
+
+	Tests the Check function with a simple problem
+	that has:
+	- objective defined
+	- two variables (one is NOT well-defined)
+	- and no constraints defined.
+	The result should throw an error relating to the bad variable.
+*/
+func TestOptimizationProblem_Check4(t *testing.T) {
+	// Constants
+	p1 := problem.NewProblem("TestOptimizationProblem_Check4")
+	v1 := p1.AddVariable()
+	v2 := symbolic.Variable{}
+
+	// Add variables to problem
+	// p1.Variables = append(p1.Variables, v1) // Already added
+	p1.Variables = append(p1.Variables, v2)
+
+	// Create good objective
+	p1.Objective = *problem.NewObjective(
+		v1, problem.SenseMaximize,
+	)
+
+	// Algorithm
+	err := p1.Check()
+	if err == nil {
+		t.Errorf("expected an error; received nil")
+	} else {
+		if !strings.Contains(
+			err.Error(),
+			v2.Check().Error(),
+		) {
+			t.Errorf("unexpected error: %v", err)
+		}
+	}
+}
+
 /*
 TestOptimizationProblem_IsLinear1
 Description:
@@ -1112,3 +1181,35 @@ func TestOptimizationProblem_IsLinear3(t *testing.T) {
 		t.Errorf("expected the problem to be non-linear; received linear")
 	}
 }
+
+/*
+TestOptimizationProblem_IsLinear4
+Description:
+
+	Tests the IsLinear function with a simple problem
+	that has a constant objective and a single, quadratic constraint.
+	The problem should be non-linear.
+*/
+func TestOptimizationProblem_IsLinear4(t *testing.T) {
+	// Constants
+	p1 := problem.NewProblem("TestOptimizationProblem_IsLinear4")
+	vv1 := p1.AddVariableVector(3)
+
+	// Add constraints
+	p1.Constraints = append(
+		p1.Constraints,
+		vv1.Transpose().Multiply(vv1).Plus(vv1).LessEq(1.0),
+	)
+
+	// Create good objective
+	p1.Objective = *problem.NewObjective(
+		symbolic.K(3.14),
+		problem.SenseMaximize,
+	)
+
+	// Algorithm
+	isLinear := p1.IsLinear()
+	if isLinear {
+		t.Errorf("expected the problem to be non-linear; received linear")
+	}
+}