Check for void nodes on JSON Patch render.

Author: josephburnett

lib/common_test.go

@@ -242,11 +242,11 @@ func fuzz(t *testing.T, aStr, bStr string) {
 		// Apply diff to A to get B.
 		patchedA, err := a.Patch(diffAB)
 		if err != nil {
-			t.Errorf("applying patch %v to %v should give %v. Got err: %v", diffAB, aStr, bStr, err)
+			t.Errorf("applying patch %v to %v should give %v. Got err: %v", diffAB.Render(), aStr, bStr, err)
 			return
 		}
 		if !patchedA.Equals(b) {
-			t.Errorf("applying patch %v to %v should give %v. Got err: %v", diffAB, aStr, bStr, patchedA)
+			t.Errorf("applying patch %v to %v should give %v. Got: %v", diffAB.Render(), aStr, bStr, patchedA)
 			return
 		}
 	}

lib/diff_write.go

@@ -59,7 +59,7 @@ func (d Diff) RenderPatch() (string, error) {
 		if len(element.OldValues) == 0 && len(element.NewValues) == 0 {
 			return "", fmt.Errorf("Cannot render empty diff element as JSON Patch op.")
 		}
-		if len(element.OldValues) == 1 {
+		if len(element.OldValues) == 1 && !isVoid(element.OldValues[0]) {
 			patch = append(patch, patchElement{
 				Op:    "test",
 				Path:  path,
@@ -71,7 +71,7 @@ func (d Diff) RenderPatch() (string, error) {
 				Value: element.OldValues[0],
 			})
 		}
-		if len(element.NewValues) == 1 {
+		if len(element.NewValues) == 1 && !isVoid(element.NewValues[0]) {
 			patch = append(patch, patchElement{
 				Op:    "add",
 				Path:  path,

lib/fuzz_backport_test.go

@@ -6,10 +6,12 @@ import "testing"
 // versions before 1.18. This is only necessary until go1.18beta2 is GA
 // and we can depend on it.
 //
-// To run fuzzing use `go1.18beta2 test -tags=test_fuzz ./lib/-run=FuzzJd`
+// To run fuzzing use `go1.18beta2 test -tags=test_fuzz ./lib/ -fuzz=FuzzJd`
 func TestFuzzBackport(t *testing.T) {
 	for _, backport := range [][2]string{{
-		"[]", "0",
+		"[]", "0", // FuzzJd/e193f6c4bfd5b8d3c12e1ac42162b2ccd7a31f9aafd466066c1ec7a95da48e1e
+	}, {
+		"{}", " ", // FuzzJd/868060b2021521d32933f40415c6f95b38fda5f5c6bdb7fa6664d046c637c03c
 	}} {
 		fuzz(t, backport[0], backport[1])
 	}

lib/testdata/fuzz/FuzzJd/868060b2021521d32933f40415c6f95b38fda5f5c6bdb7fa6664d046c637c03c

@@ -0,0 +1,3 @@
+go test fuzz v1
+string("{}")
+string(" ")