Build formulas recursively

pkg/package/package.go

@@ -143,6 +143,12 @@ func (p *DefaultPackage) BuildFormula() ([]bf.Formula, error) {
 		}
 		B := bf.Var(encodedB)
 
+		f, err := required.BuildFormula()
+		if err != nil {
+			return nil, err
+		}
+		formulas = append(formulas, f...)
+
 		formulas = append(formulas, bf.Or(bf.Not(A), bf.And(A, B)))
 
 	}
@@ -153,10 +159,17 @@ func (p *DefaultPackage) BuildFormula() ([]bf.Formula, error) {
 			return nil, err
 		}
 		B := bf.Var(encodedB)
+
+		f, err := required.BuildFormula()
+		if err != nil {
+			return nil, err
+		}
+
 		formulas = append(formulas, bf.Or(bf.Not(A),
 			bf.And(A, bf.Not(B))))
+		formulas = append(formulas, f...)
 
 	}
 
-	return formulas, nil
+	return []bf.Formula{bf.Implies(A, bf.And(formulas...))}, nil
 }

pkg/solver/solver_test.go

@@ -37,10 +37,27 @@ var _ = Describe("Solver", func() {
 
 			solution, err := s.Solve()
 			Expect(err).ToNot(HaveOccurred())
+			Expect(solution).To(ContainElement(A.IsFlagged(true)))
 			Expect(solution).To(ContainElement(B.IsFlagged(true)))
 			Expect(solution).To(ContainElement(C.IsFlagged(true)))
-			// Expect(solution).To(ContainElement(A.IsFlagged(true)))
 		})
+		It("Solves correctly more complex ones", func() {
+			C := pkg.NewPackage("C", "", []pkg.Package{}, []pkg.Package{})
+			D := pkg.NewPackage("D", "", []pkg.Package{}, []pkg.Package{})
+			B := pkg.NewPackage("B", "", []pkg.Package{D}, []pkg.Package{})
+			A := pkg.NewPackage("A", "", []pkg.Package{B}, []pkg.Package{})
+			C.IsFlagged(true) // installed
+
+			s := NewSolver([]pkg.Package{A.IsFlagged(true)}, []pkg.Package{C})
+
+			solution, err := s.Solve()
+			Expect(solution).To(ContainElement(C.IsFlagged(true)))
+			Expect(solution).To(ContainElement(D.IsFlagged(true)))
+			Expect(solution).To(ContainElement(B.IsFlagged(true)))
+
+			Expect(err).ToNot(HaveOccurred())
+		})
+
 	})
 
 	Context("Conflict set", func() {