Fix scientific notation decoding and add encoding test cases

decode.go

@@ -488,6 +488,21 @@ func (d *Decoder) fileToNode(f *ast.File) ast.Node {
 func (d *Decoder) convertValue(v reflect.Value, typ reflect.Type, src ast.Node) (reflect.Value, error) {
 	if typ.Kind() != reflect.String {
 		if !v.Type().ConvertibleTo(typ) {
+
+			// Special case for "strings -> floats" aka scientific notation
+			// If the destination type is a float and the source type is a string, check if we can 
+			// use strconv.ParseFloat to convert the string to a float.
+			if (typ.Kind() == reflect.Float32 || typ.Kind() == reflect.Float64) &&
+				v.Type().Kind() == reflect.String {
+				if f, err := strconv.ParseFloat(v.String(), 64); err == nil {
+					if typ.Kind() == reflect.Float32 {
+						return reflect.ValueOf(float32(f)), nil
+					} else if typ.Kind() == reflect.Float64 {
+						return reflect.ValueOf(f), nil
+					}
+					// else, fall through to the error below
+				}
+			}
 			return reflect.Zero(typ), errTypeMismatch(typ, v.Type(), src.GetToken())
 		}
 		return v.Convert(typ), nil

decode_test.go

@@ -289,6 +289,10 @@ func TestDecoder(t *testing.T) {
 			"v: 18446744073709551616",
 			map[string]float32{"v": float32(math.MaxUint64 + 1)},
 		},
+		{
+			"v: 1e-06",
+			map[string]float32{"v": 1e-6},
+		},
 
 		// float64
 		{
@@ -307,6 +311,10 @@ func TestDecoder(t *testing.T) {
 			"v: 18446744073709551616",
 			map[string]float64{"v": float64(math.MaxUint64 + 1)},
 		},
+		{
+			"v: 1e-06",
+			map[string]float64{"v": 1e-06},
+		},
 
 		// Timestamps
 		{
@@ -2932,4 +2940,4 @@ func TestMapKeyCustomUnmarshaler(t *testing.T) {
 	if val != "value" {
 		t.Fatalf("expected to have value \"value\", but got %q", val)
 	}
-}
+}

encode_test.go

@@ -80,6 +80,16 @@ func TestEncoder(t *testing.T) {
 			map[string]float32{"v": 0.99},
 			nil,
 		},
+		{
+			"v: 1e-06\n",
+			map[string]float32{"v": 1e-06},
+			nil,
+		},
+		{
+			"v: 1e-06\n",
+			map[string]float64{"v": 0.000001},
+			nil,
+		},
 		{
 			"v: 0.123456789\n",
 			map[string]float64{"v": 0.123456789},
@@ -100,6 +110,16 @@ func TestEncoder(t *testing.T) {
 			map[string]float64{"v": 1000000},
 			nil,
 		},
+		{
+			"v: 1e-06\n",
+			map[string]float64{"v": 0.000001},
+			nil,
+		},
+		{
+			"v: 1e-06\n",
+			map[string]float64{"v": 1e-06},
+			nil,
+		},
 		{
 			"v: .inf\n",
 			map[string]interface{}{"v": math.Inf(0)},