GODRIVER-756 fix formatting of numbers with exponents in JSON

Change-Id: I9c8fe82ab5ddc735206228abfd7bc943e143f41a

Author: Isabella Siu

bson/bson.go

@@ -12,10 +12,6 @@
 package bson
 
 import (
-	"math"
-	"strconv"
-	"strings"
-
 	"github.com/mongodb/mongo-go-driver/bson/primitive"
 )
 
@@ -62,23 +58,3 @@ type M = primitive.M
 // 		bson.A{"bar", "world", 3.14159, bson.D{{"qux", 12345}}}
 //
 type A = primitive.A
-
-func formatDouble(f float64) string {
-	var s string
-	if math.IsInf(f, 1) {
-		s = "Infinity"
-	} else if math.IsInf(f, -1) {
-		s = "-Infinity"
-	} else if math.IsNaN(f) {
-		s = "NaN"
-	} else {
-		// Print exactly one decimalType place for integers; otherwise, print as many are necessary to
-		// perfectly represent it.
-		s = strconv.FormatFloat(f, 'G', -1, 64)
-		if !strings.ContainsRune(s, '.') {
-			s += ".0"
-		}
-	}
-
-	return s
-}

bson/bson_corpus_spec_test.go

@@ -11,6 +11,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
+	"math"
 	"path"
 	"strconv"
 	"strings"
@@ -129,6 +130,26 @@ func unescapeUnicode(s, bsonType string) string {
 	return newS
 }
 
+func formatDouble(f float64) string {
+	var s string
+	if math.IsInf(f, 1) {
+		s = "Infinity"
+	} else if math.IsInf(f, -1) {
+		s = "-Infinity"
+	} else if math.IsNaN(f) {
+		s = "NaN"
+	} else {
+		// Print exactly one decimalType place for integers; otherwise, print as many are necessary to
+		// perfectly represent it.
+		s = strconv.FormatFloat(f, 'G', -1, 64)
+		if !strings.ContainsRune(s, 'E') && !strings.ContainsRune(s, '.') {
+			s += ".0"
+		}
+	}
+
+	return s
+}
+
 func normalizeCanonicalDouble(t *testing.T, key string, cEJ string) string {
 	// Unmarshal string into map
 	cEJMap := make(map[string]map[string]string)

bson/bsonrw/extjson_writer.go

@@ -621,7 +621,7 @@ func formatDouble(f float64) string {
 		// Print exactly one decimalType place for integers; otherwise, print as many are necessary to
 		// perfectly represent it.
 		s = strconv.FormatFloat(f, 'G', -1, 64)
-		if !strings.ContainsRune(s, '.') {
+		if !strings.ContainsRune(s, 'E') && !strings.ContainsRune(s, '.') {
 			s += ".0"
 		}
 	}

bson/bsonrw/extjson_writer_test.go

@@ -249,4 +249,12 @@ func TestExtJSONValueWriter(t *testing.T) {
 			}
 		})
 	})
+
+	t.Run("FormatDoubleWithExponent", func(t *testing.T) {
+		want := "3E-12"
+		got := formatDouble(float64(0.000000000003))
+		if got != want {
+			t.Errorf("Did not receive expected string. got %s: want %s", got, want)
+		}
+	})
 }