From 8c1b3e96c4d5bb879b7ee8d02012231934357911 Mon Sep 17 00:00:00 2001
From: Yuri Shkuro <ys@uber.com>
Date: Fri, 2 Jun 2017 16:57:47 -0400
Subject: [PATCH] Do not omit empty arrays in JSON

---
 model/converter/json/fixtures/ui_01.json | 23 ++++++++++++++++++-----
 model/json/fixture.json                  | 20 +++++++++++++++-----
 model/json/model.go                      | 14 +++++++-------
 model/json/model_test.go                 |  5 ++++-
 4 files changed, 44 insertions(+), 18 deletions(-)

diff --git a/model/converter/json/fixtures/ui_01.json b/model/converter/json/fixtures/ui_01.json
index 27a5028715c..91829c7587c 100644
--- a/model/converter/json/fixtures/ui_01.json
+++ b/model/converter/json/fixtures/ui_01.json
@@ -5,8 +5,10 @@
       "traceID": "1",
       "spanID": "2",
       "operationName": "test-general-conversion",
+      "references": [],
       "startTime": 1485467191639875,
       "duration": 5,
+      "tags": [],
       "logs": [
         {
           "timestamp": 1485467191639875,
@@ -29,12 +31,14 @@
           ]
         }
       ],
-      "processID": "p1"
+      "processID": "p1",
+      "warnings": null
     },
     {
       "traceID": "1",
       "spanID": "2",
       "operationName": "some-operation",
+      "references": [],
       "startTime": 1485467191639875,
       "duration": 5,
       "tags": [
@@ -64,7 +68,9 @@
           "value": "AAAwOQ=="
         }
       ],
-      "processID": "p1"
+      "logs": [],
+      "processID": "p1",
+      "warnings": null
     },
     {
       "traceID": "1",
@@ -79,7 +85,10 @@
       ],
       "startTime": 1485467191639875,
       "duration": 5,
-      "processID": "p2"
+      "tags": [],
+      "logs": [],
+      "processID": "p2",
+      "warnings": null
     },
     {
       "traceID": "1",
@@ -104,6 +113,8 @@
       ],
       "startTime": 1485467191639875,
       "duration": 5,
+      "tags": [],
+      "logs": [],
       "processID": "p2",
       "warnings": [
         "some span warning"
@@ -112,10 +123,12 @@
   ],
   "processes": {
     "p1": {
-      "serviceName": "service-x"
+      "serviceName": "service-x",
+      "tags": []
     },
     "p2": {
-      "serviceName": "service-y"
+      "serviceName": "service-y",
+      "tags": []
     }
   },
   "warnings": [
diff --git a/model/json/fixture.json b/model/json/fixture.json
index e344bdf9c05..29c27c8131f 100644
--- a/model/json/fixture.json
+++ b/model/json/fixture.json
@@ -5,9 +5,13 @@
       "traceID": "abc0",
       "spanID": "abc0",
       "operationName": "root-span",
+      "references": null,
       "startTime": 1000,
       "duration": 500,
-      "processID": "p1"
+      "tags": null,
+      "logs": null,
+      "processID": "p1",
+      "warnings": null
     },
     {
       "traceID": "abc0",
@@ -56,7 +60,8 @@
           ]
         }
       ],
-      "processID": "p2"
+      "processID": "p2",
+      "warnings": null
     },
     {
       "traceID": "abc0",
@@ -71,12 +76,16 @@
       ],
       "startTime": 1000,
       "duration": 500,
-      "processID": "p2"
+      "tags": null,
+      "logs": null,
+      "processID": "p2",
+      "warnings": null
     }
   ],
   "processes": {
     "p1": {
-      "serviceName": "service_1"
+      "serviceName": "service_1",
+      "tags": null
     },
     "p2": {
       "serviceName": "service_2",
@@ -88,5 +97,6 @@
         }
       ]
     }
-  }
+  },
+  "warnings": null
 }
diff --git a/model/json/model.go b/model/json/model.go
index b700dd3d69d..bd93c136b79 100644
--- a/model/json/model.go
+++ b/model/json/model.go
@@ -63,7 +63,7 @@ type Trace struct {
 	TraceID   TraceID               `json:"traceID"`
 	Spans     []Span                `json:"spans"`
 	Processes map[ProcessID]Process `json:"processes"`
-	Warnings  []string              `json:"warnings,omitempty"`
+	Warnings  []string              `json:"warnings"`
 }
 
 // Span is a span denoting a piece of work in some infrastructure
@@ -72,13 +72,13 @@ type Span struct {
 	SpanID        SpanID      `json:"spanID"`
 	Flags         uint32      `json:"flags,omitempty"`
 	OperationName string      `json:"operationName"`
-	References    []Reference `json:"references,omitempty"`
+	References    []Reference `json:"references"`
 	StartTime     uint64      `json:"startTime"` // microseconds since Unix epoch
 	Duration      uint64      `json:"duration"`  // microseconds
-	Tags          []KeyValue  `json:"tags,omitempty"`
-	Logs          []Log       `json:"logs,omitempty"`
+	Tags          []KeyValue  `json:"tags"`
+	Logs          []Log       `json:"logs"`
 	ProcessID     ProcessID   `json:"processID"`
-	Warnings      []string    `json:"warnings,omitempty"`
+	Warnings      []string    `json:"warnings"`
 }
 
 // Reference is a reference from one span to another
@@ -91,13 +91,13 @@ type Reference struct {
 // Process is the process emitting a set of spans
 type Process struct {
 	ServiceName string     `json:"serviceName"`
-	Tags        []KeyValue `json:"tags,omitempty"`
+	Tags        []KeyValue `json:"tags"`
 }
 
 // Log is a log emitted in a span
 type Log struct {
 	Timestamp uint64     `json:"timestamp"`
-	Fields    []KeyValue `json:"fields,omitempty"`
+	Fields    []KeyValue `json:"fields"`
 }
 
 // KeyValue is a a key-value pair with typed value.
diff --git a/model/json/model_test.go b/model/json/model_test.go
index 03eeb6728b1..fc8046b4ef4 100644
--- a/model/json/model_test.go
+++ b/model/json/model_test.go
@@ -46,7 +46,10 @@ func TestModel(t *testing.T) {
 	err = encoder.Encode(&trace)
 	require.NoError(t, err)
 
-	assert.Equal(t, string(in), string(out.Bytes()))
+	if !assert.Equal(t, string(in), string(out.Bytes())) {
+		err := ioutil.WriteFile("fixture-actual.json", out.Bytes(), 0644)
+		assert.NoError(t, err)
+	}
 }
 
 func TestFromFileErrors(t *testing.T) {