func TestAbsorb(t *testing.T) {
m1 := mat1()
cmp := m1.Comp
m3 := mat3()
m1.Absorb(m3)
assert.Eq(t, m1.Qty(), qty1+qty3)
assert.Eq(t, m3.Qty(), zero)
assert.Ne(t, m1.Comp, cmp)
}
func TestExtractComp_Good(t *testing.T) {
m := mat1()
mcmp := m.Comp
ecmp := mat2().Comp
var qty float64 = 1.0
e, err := m.ExtractComp(qty, ecmp)
assert.NoErr(t, err).Fatal()
assert.Eq(t, m.Qty(), qty1-qty)
assert.Eq(t, e.Qty(), qty)
assert.Ne(t, m.Comp, mcmp)
assert.Eq(t, e.Comp, ecmp)
}