GODRIVER-1210 Add String for readpref.Mode and readpref.Readpref (#382)

Author: bartle-stripe

mongo/readpref/mode.go

@@ -54,3 +54,21 @@ func ModeFromString(mode string) (Mode, error) {
 	}
 	return Mode(0), fmt.Errorf("unknown read preference %v", mode)
 }
+
+// String returns the string representation of mode.
+func (mode Mode) String() string {
+	switch mode {
+	case PrimaryMode:
+		return "primary"
+	case PrimaryPreferredMode:
+		return "primaryPreferred"
+	case SecondaryMode:
+		return "secondary"
+	case SecondaryPreferredMode:
+		return "secondaryPreferred"
+	case NearestMode:
+		return "nearest"
+	default:
+		return "unknown"
+	}
+}

mongo/readpref/mode_test.go

@@ -0,0 +1,35 @@
+// Copyright (C) MongoDB, Inc. 2020-present.
+
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package readpref
+
+import (
+	"testing"
+
+	"go.mongodb.org/mongo-driver/internal/testutil/assert"
+)
+
+func TestMode_String(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name string
+		mode Mode
+	}{
+		{"primary", PrimaryMode},
+		{"primaryPreferred", PrimaryPreferredMode},
+		{"secondary", SecondaryMode},
+		{"secondaryPreferred", SecondaryPreferredMode},
+		{"nearest", NearestMode},
+		{"unknown", Mode(42)},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.name, tc.mode.String(), "expected %q, got %q", tc.name, tc.mode.String())
+		})
+	}
+}

mongo/readpref/readpref.go

@@ -7,7 +7,9 @@
 package readpref // import "go.mongodb.org/mongo-driver/mongo/readpref"
 
 import (
+	"bytes"
 	"errors"
+	"fmt"
 	"time"
 
 	"go.mongodb.org/mongo-driver/tag"
@@ -104,3 +106,26 @@ func (r *ReadPref) TagSets() []tag.Set {
 func (r *ReadPref) HedgeEnabled() *bool {
 	return r.hedgeEnabled
 }
+
+// String returns a human-readable description of the read preference.
+func (r *ReadPref) String() string {
+	var b bytes.Buffer
+	b.WriteString(r.mode.String())
+	delim := "("
+	if r.maxStalenessSet {
+		fmt.Fprintf(&b, "%smaxStaleness=%v", delim, r.maxStaleness)
+		delim = " "
+	}
+	for _, tagSet := range r.tagSets {
+		fmt.Fprintf(&b, "%stagSet=%s", delim, tagSet.String())
+		delim = " "
+	}
+	if r.hedgeEnabled != nil {
+		fmt.Fprintf(&b, "%shedgeEnabled=%v", delim, *r.hedgeEnabled)
+		delim = " "
+	}
+	if delim != "(" {
+		b.WriteString(")")
+	}
+	return b.String()
+}

mongo/readpref/readpref_test.go

@@ -134,3 +134,25 @@ func TestHedge(t *testing.T) {
 		assert.True(t, *enabled, "expected HedgeEnabled to return true, got false")
 	})
 }
+
+func TestReadPref_String(t *testing.T) {
+	t.Run("ReadPref.String() with all options", func(t *testing.T) {
+		readPref := Nearest(
+			WithMaxStaleness(120*time.Second),
+			WithTagSets(tag.Set{{"a", "1"}, {"b", "2"}}, tag.Set{{"q", "5"}, {"r", "6"}}),
+			WithHedgeEnabled(true),
+		)
+		expected := "nearest(maxStaleness=2m0s tagSet=a=1,b=2 tagSet=q=5,r=6 hedgeEnabled=true)"
+		assert.Equal(t, expected, readPref.String(), "expected %q, got %q", expected, readPref.String())
+	})
+	t.Run("ReadPref.String() with one option", func(t *testing.T) {
+		readPref := Secondary(WithTags("a", "1", "b", "2"))
+		expected := "secondary(tagSet=a=1,b=2)"
+		assert.Equal(t, expected, readPref.String(), "expected %q, got %q", expected, readPref.String())
+	})
+	t.Run("ReadPref.String() with no options", func(t *testing.T) {
+		readPref := Primary()
+		expected := "primary"
+		assert.Equal(t, expected, readPref.String(), "expected %q, got %q", expected, readPref.String())
+	})
+}

tag/tag.go

@@ -6,12 +6,22 @@
 
 package tag // import "go.mongodb.org/mongo-driver/tag"
 
+import (
+	"bytes"
+	"fmt"
+)
+
 // Tag is a name/vlaue pair.
 type Tag struct {
 	Name  string
 	Value string
 }
 
+// String returns a human-readable human-readable description of the tag.
+func (tag Tag) String() string {
+	return fmt.Sprintf("%s=%s", tag.Name, tag.Value)
+}
+
 // NewTagSetFromMap creates a new tag set from a map.
 func NewTagSetFromMap(m map[string]string) Set {
 	var set Set
@@ -55,3 +65,15 @@ func (ts Set) ContainsAll(other []Tag) bool {
 
 	return true
 }
+
+// String returns a human-readable human-readable description of the tagset.
+func (ts Set) String() string {
+	var b bytes.Buffer
+	for i, tag := range ts {
+		if i > 0 {
+			b.WriteString(",")
+		}
+		b.WriteString(tag.String())
+	}
+	return b.String()
+}

tag/tag_test.go

@@ -10,8 +10,16 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/require"
+	"go.mongodb.org/mongo-driver/internal/testutil/assert"
 )
 
+func TestTag_String(t *testing.T) {
+	t.Parallel()
+
+	tag := Tag{Name: "a", Value: "1"}
+	assert.Equal(t, "a=1", tag.String(), `expected "a=1", got %q`, tag.String())
+}
+
 func TestTagSets_NewTagSet(t *testing.T) {
 	t.Parallel()
 
@@ -76,3 +84,13 @@ func TestTagSets_ContainsAll(t *testing.T) {
 	test = Set{Tag{Name: "a", Value: "2"}, Tag{Name: "b", Value: "2"}}
 	require.False(t, ts.ContainsAll(test))
 }
+
+func TestTagSets_String(t *testing.T) {
+	t.Parallel()
+
+	ts := Set{
+		Tag{Name: "a", Value: "1"},
+		Tag{Name: "b", Value: "2"},
+	}
+	assert.Equal(t, "a=1,b=2", ts.String(), `expected "a=1,b=2", got %q`, ts.String())
+}