Marshal MicroTime to json and proto at the same precision

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/micro_time_proto.go

@@ -27,9 +27,12 @@ func (m *MicroTime) ProtoMicroTime() *Timestamp {
 	if m == nil {
 		return &Timestamp{}
 	}
+
+	// truncate precision to microseconds to match JSON marshaling/unmarshaling
+	truncatedNanoseconds := time.Duration(m.Time.Nanosecond()).Truncate(time.Microsecond)
 	return &Timestamp{
 		Seconds: m.Time.Unix(),
-		Nanos:   int32(m.Time.Nanosecond()),
+		Nanos:   int32(truncatedNanoseconds),
 	}
 }
 
@@ -51,7 +54,10 @@ func (m *MicroTime) Unmarshal(data []byte) error {
 	if err := p.Unmarshal(data); err != nil {
 		return err
 	}
-	m.Time = time.Unix(p.Seconds, int64(p.Nanos)).Local()
+
+	// truncate precision to microseconds to match JSON marshaling/unmarshaling
+	truncatedNanoseconds := time.Duration(p.Nanos).Truncate(time.Microsecond)
+	m.Time = time.Unix(p.Seconds, int64(truncatedNanoseconds)).Local()
 	return nil
 }
 

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/micro_time_test.go

@@ -118,7 +118,7 @@ func TestMicroTimeProto(t *testing.T) {
 		input MicroTime
 	}{
 		{MicroTime{}},
-		{DateMicro(1998, time.May, 5, 1, 5, 5, 50, time.Local)},
+		{DateMicro(1998, time.May, 5, 1, 5, 5, 1000, time.Local)},
 		{DateMicro(1998, time.May, 5, 5, 5, 5, 0, time.Local)},
 	}
 
@@ -253,3 +253,68 @@ func TestMicroTimeIsZero(t *testing.T) {
 		})
 	}
 }
+
+func TestMicroTimeUnmarshalJSONAndProtoEqual(t *testing.T) {
+	cases := []struct {
+		name   string
+		input  MicroTime
+		result bool
+	}{
+		{"nanosecond level precision", UnixMicro(123, 123123123), true},
+		{"microsecond level precision", UnixMicro(123, 123123000), true},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			jsonData, err := c.input.MarshalJSON()
+			if err != nil {
+				t.Fatalf("Failed to marshal input to JSON: '%v': %v", c.input, err)
+			}
+
+			protoData, err := c.input.Marshal()
+			if err != nil {
+				t.Fatalf("Failed to marshal input to proto: '%v': %v", c.input, err)
+			}
+
+			var tJSON, tProto MicroTime
+			if err = tJSON.UnmarshalJSON(jsonData); err != nil {
+				t.Fatalf("Failed to unmarshal JSON: '%v': %v", jsonData, err)
+			}
+			if err = tProto.Unmarshal(protoData); err != nil {
+				t.Fatalf("Failed to unmarshal proto: '%v': %v", protoData, err)
+			}
+
+			result := tJSON.Equal(&tProto)
+			if result != c.result {
+				t.Errorf("Failed equality test for '%v': expected %+v, got %+v", c.input, c.result, result)
+			}
+		})
+	}
+}
+
+func TestMicroTimeProtoUnmarshalRaw(t *testing.T) {
+	cases := []struct {
+		name     string
+		input    []byte
+		expected MicroTime
+	}{
+		// input is generated by Timestamp{123, 123123123}.Marshal()
+		{"nanosecond level precision", []byte{8, 123, 16, 179, 235, 218, 58}, UnixMicro(123, 123123000)},
+		// input is generated by Timestamp{123, 123123000}.Marshal()
+		{"microsecond level precision", []byte{8, 123, 16, 184, 234, 218, 58}, UnixMicro(123, 123123000)},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			var actual MicroTime
+			if err := actual.Unmarshal(c.input); err != nil {
+				t.Fatalf("Failed to unmarshal proto: '%v': %v", c.input, err)
+			}
+
+			if !actual.Equal(&c.expected) {
+				t.Errorf("Failed unmarshal from nanosecond-precise raw for '%v': expected %+v, got %+v", c.input, c.expected, actual)
+			}
+		})
+	}
+
+}