implement amount.go:Amount:AbsoluteValue

digits-work-sample-go.d/amount.go

@@ -44,6 +44,13 @@ var localizedLanguagePrinter = func() *message.Printer {
 	return message.NewPrinter(result)
 }()
 
+func (amount Amount) AbsoluteValue() Amount {
+	if amount < 0 {
+		return -1.0 * amount
+	}
+	return amount
+}
+
 // Rounded rounds a float to the number of places specified.
 func (amount Amount) Rounded(places int) Amount {
 	p := math.Pow10(places)

digits-work-sample-go.d/amount_test.go

@@ -87,3 +87,33 @@ func TestFormatUSD(t *testing.T) {
 		})
 	}
 }
+
+func TestAmountAbsoluteValue(t *testing.T) {
+	cases := map[string]struct {
+		input Amount
+		want  Amount
+	}{
+		"zero": {
+			input: Amount(0.0),
+			want:  Amount(0.0),
+		},
+		"positive unchanged": {
+			input: Amount(1.0),
+			want:  Amount(1.0),
+		},
+		"negative unchanged": {
+			input: Amount(-0.000001),
+			want:  Amount(0.000001),
+		},
+	}
+
+	for name, td := range cases {
+		tt := td // go bug through 1.21+ requires allocating a new variable or setting a go env for experimental features as of go 1.20 (1.21?)
+		t.Run(name, func(t *testing.T) {
+			got := tt.input.AbsoluteValue()
+			if got != tt.want {
+				t.Errorf("got \n\t%v, want\n\t%v", got, tt.want)
+			}
+		})
+	}
+}