1 files changed, 105 insertions, 0 deletions
diff --git a/lay/strain/solve_test.go b/lay/strain/solve_test.go
new file mode 100644
index 0000000..61ab7e6
--- /dev/null
+++ b/lay/strain/solve_test.go
@@ -0,0 +1,105 @@
+package strain_test
+
+import (
+	"testing"
+	"image"
+	"slices"
+
+	"github.com/lithdew/casso"
+
+	"github.com/faiface/gui/style"
+	"github.com/faiface/gui/lay/strain"
+)
+
+type solverTest struct {
+	t *testing.T
+	*style.Style
+	*strain.Solver
+}
+
+func newSolverTest(t *testing.T, constraints []<-chan strain.Constraint) solverTest {
+	styl, err := style.New()
+	if err != nil {
+		t.Fatal(err)
+	}
+	solver, err := strain.NewSolver(styl, constraints)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return solverTest{t, styl, solver}
+}
+
+func (st solverTest) Close() {
+	st.Solver.Close()
+	if err := st.Style.Close(); err != nil {
+		st.t.Error(err)
+	}
+}
+
+func (st solverTest) addConstraint(op casso.Op, lhs, rhs casso.Symbol) {
+	if err := st.Solver.AddConstraint(op, lhs, rhs); err != nil {
+		st.t.Error(err)
+	}
+}
+
+func (st solverTest) solve(container image.Rectangle, wantFields []image.Rectangle) {
+	fields, err := st.Solver.Solve(container)
+	if err != nil {
+		st.t.Errorf("Solve(%v): %v; want %v", container, err, wantFields)
+	}
+	if !slices.Equal(fields, wantFields) {
+		st.t.Errorf("Solve(%v) = %v; want %v", container, fields, wantFields)
+	}
+}
+
+// No constraints and zero-sized container.
+func TestTrivial(t *testing.T) {
+	t.Parallel()
+	st := newSolverTest(t, nil)
+	defer st.Close()
+	fields, err := st.Solver.Solve(image.ZR)
+	if err != nil {
+		t.Error(err)
+	}
+	if len(fields) != 0 {
+		t.Errorf("expected 0 fields; got %d", len(fields))
+	}
+}
+
+// One field that occupies the whole container.
+func TestSingleField(t *testing.T) {
+	// Setup
+	t.Parallel()
+	constraints := make(chan strain.Constraint)
+	st := newSolverTest(t, []<-chan strain.Constraint{constraints})
+	defer st.Close()
+	defer close(constraints)
+
+	// Add constraints
+	container := st.Solver.Container()
+	field := st.Solver.Field(0)
+	st.addConstraint(casso.EQ, field.Origin.X, container.Origin.X)
+	st.addConstraint(casso.EQ, field.Origin.Y, container.Origin.Y)
+	st.addConstraint(casso.EQ, field.Size.X, container.Size.X)
+	st.addConstraint(casso.EQ, field.Size.Y, container.Size.Y)
+
+	// Solve
+	for _, container := range []image.Rectangle{
+		image.ZR,
+		image.Rectangle{image.ZP, image.Pt(800, 600)},
+		image.Rectangle{image.Pt(12, 34), image.Pt(123, 456)},
+	} {
+		// field == container
+		st.solve(container, []image.Rectangle{container})
+	}
+}
+
+// Solver with only layout constaints, no field constraints.
+func TestLayConstrs(t *testing.T) {
+	t.Parallel()
+
+	st := newSolverTest(t, nil)
+	defer st.Close()
+
+	t.Fail() // TODO
+}