go/staking/api: Add PrettyPrintCommissionScheduleIndexInfixes() helper

.changelog/3265.feature.1.md

@@ -0,0 +1 @@
+ go/staking/api: Add `PrettyPrintCommissionScheduleIndexInfixes()` helper

go/staking/api/prettyprint.go

@@ -1,7 +1,9 @@
 package api
 
 import (
+	"context"
 	"fmt"
+	"strings"
 
 	"github.com/oasisprotocol/oasis-core/go/common/prettyprint"
 	"github.com/oasisprotocol/oasis-core/go/common/quantity"
@@ -20,3 +22,17 @@ func PrettyPrintCommissionRatePercentage(rateNumerator quantity.Quantity) string
 	denominatorExp := commissionRateDenominatorExponent - 2
 	return fmt.Sprintf("%s%%", prettyprint.QuantityFrac(rateNumerator, denominatorExp))
 }
+
+// PrettyPrintCommissionScheduleIndexInfixes returns two infixes:
+// - indexInfix holds the infix to use to pretty print the given commission
+//   schedule rate (bound) index
+// - emptyInfix holds the infix to use to pretty print an empty string of an
+//   equivalent length
+func PrettyPrintCommissionScheduleIndexInfixes(ctx context.Context) (indexInfix, emptyInfix string) {
+	index, ok := ctx.Value(prettyprint.ContextKeyCommissionScheduleIndex).(int)
+	if ok {
+		indexInfix = fmt.Sprintf("(%d) ", index+1)
+		emptyInfix = strings.Repeat(" ", len(indexInfix))
+	}
+	return
+}

go/staking/api/prettyprint_test.go

@@ -1,10 +1,12 @@
 package api
 
 import (
+	"context"
 	"testing"
 
 	"github.com/stretchr/testify/require"
 
+	"github.com/oasisprotocol/oasis-core/go/common/prettyprint"
 	"github.com/oasisprotocol/oasis-core/go/common/quantity"
 )
 
@@ -29,3 +31,26 @@ func TestPrettyPrintCommissionRatePercentage(t *testing.T) {
 		require.Equal(t.expectedRate, rate, "obtained pretty print didn't match expected value")
 	}
 }
+
+func TestPrettyPrintCommissionScheduleIndexInfixes(t *testing.T) {
+	require := require.New(t)
+
+	for _, t := range []struct {
+		expectedIndexInfix string
+		expectedEmptyInfix string
+		index              int
+		indexPresent       bool
+	}{
+		{"(1) ", "    ", 0, true},
+		{"(2) ", "    ", 1, true},
+		{"(10) ", "     ", 9, true},
+		{"(123) ", "      ", 122, true},
+		{"(2345678) ", "          ", 2345677, true},
+	} {
+		require.Equal(len(t.expectedIndexInfix), len(t.expectedEmptyInfix), "expected index and empty infixes should be of equal length")
+		ctx := context.WithValue(context.Background(), prettyprint.ContextKeyCommissionScheduleIndex, t.index)
+		indexInfix, emptyInfix := PrettyPrintCommissionScheduleIndexInfixes(ctx)
+		require.Equal(t.expectedIndexInfix, indexInfix, "obtained index infix didn't match expected value")
+		require.Equal(t.expectedEmptyInfix, emptyInfix, "obtained empty infix didn't match expected value")
+	}
+}