// Duplicate the test executable into the path at testGo, for $PATH.
		// If the OS supports symlinks, use them instead of copying bytes.
		testExe, err := os.Executable()
		if err != nil {
			log.Fatal(err)
		}
		if err := os.Symlink(testExe, testGo); err != nil {
			// Otherwise, copy the bytes.
			src, err := os.Open(testExe)
			if err != nil {
				log.Fatal(err)
			}
			defer src.Close()

	for i, test := range tests {
		test.a.Sub(test.b)
		if test.a.Cmp(test.expected) != 0 {
			t.Errorf("[%d] Expected %q, got %q", i, test.expected.String(), test.a.String())
		}
	}
}

func TestNeg(t *testing.T) {
	tests := []struct {
		a        Quantity
		b        Quantity
		expected Quantity
	}{
		{a: intQuantity(0, 0, DecimalSI), expected: intQuantity(0, 0, DecimalSI)},