exploring support for type matcher

examples/__snapshots__/matchJSON_test.snap

@@ -88,3 +88,15 @@
  }
 }
 ---
+
+[TestMatchers/type_matcher - 1]
+{
+ "data": "<Type:float64>"
+}
+---
+
+[TestMatchers/type_matcher - 2]
+{
+ "metadata": "<Type:map[string]interface {}>"
+}
+---

examples/matchJSON_test.go

@@ -178,4 +178,13 @@ func TestMatchers(t *testing.T) {
 
 		snaps.MatchJSON(t, body, match.Any("data.createdAt"))
 	})
+
+	t.Run("type matcher", func(t *testing.T) {
+		snaps.MatchJSON(t, `{"data":10}`, match.Type[float64]("data"))
+		snaps.MatchJSON(
+			t,
+			`{"metadata":{"timestamp":"1687108093142"}}`,
+			match.Type[map[string]interface{}]("metadata"),
+		)
+	})
 }

match/type.go

@@ -0,0 +1,75 @@
+package match
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+type typeMatcher[T any] struct {
+	paths            []string
+	errOnMissingPath bool
+	name             string
+	_type            interface{}
+}
+
+func Type[T any](paths ...string) *typeMatcher[T] {
+	return &typeMatcher[T]{
+		paths:            paths,
+		errOnMissingPath: true,
+		name:             "Type",
+		_type:            *new(T),
+	}
+}
+
+// ErrOnMissingPath determines if matcher will fail in case of trying to access a json path
+// that doesn't exist
+func (t *typeMatcher[T]) ErrOnMissingPath(e bool) *typeMatcher[T] {
+	t.errOnMissingPath = e
+	return t
+}
+
+func (t typeMatcher[T]) JSON(s []byte) ([]byte, []MatcherError) {
+	var errs []MatcherError
+	json := s
+
+	for _, path := range t.paths {
+		r := gjson.GetBytes(json, path)
+		if !r.Exists() {
+			if t.errOnMissingPath {
+				errs = append(errs, MatcherError{
+					Reason:  errors.New("path does not exist"),
+					Matcher: t.name,
+					Path:    path,
+				})
+			}
+			continue
+		}
+
+		_, ok := r.Value().(T)
+		value := fmt.Sprintf("<Type:%T>", *new(T))
+		if !ok {
+			value = fmt.Sprintf("<Type:%T>", r.Value())
+		}
+
+		j, err := sjson.SetBytesOptions(json, path, value, &sjson.Options{
+			Optimistic:     true,
+			ReplaceInPlace: true,
+		})
+		if err != nil {
+			errs = append(errs, MatcherError{
+				Reason:  err,
+				Matcher: t.name,
+				Path:    path,
+			})
+
+			continue
+		}
+
+		json = j
+	}
+
+	return json, errs
+}