fix data mutation issue (#12)

* fix data mutation issue

* update unit tests

Author: farhan-sauce

src/index.ts

@@ -51,9 +51,12 @@ export default class Tracelib {
             throw new Error('MainTrack is missing in traceLog')
         }
 
+        // We are facing data mutaion issue in devtools, to avoid it cloning syncEvents
+        const syncEvents = mainTrack.syncEvents().slice()
+
         return {
             ...timelineUtils.statsForTimeRange(
-                mainTrack.syncEvents(), startTime, endTime
+                syncEvents, startTime, endTime
             ),
             startTime,
             endTime,

tests/__snapshots__/index.test.ts.snap

@@ -1,6 +1,6 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`getSummary: should get summary data 1`] = `
+exports[`getSummary should get summary data 1`] = `
 Object {
   "endTime": 289961229.717,
   "idle": 52.38300037384033,
@@ -12,7 +12,31 @@ Object {
 }
 `;
 
-exports[`getWarningCounts: should get warning counts 1`] = `
+exports[`getSummary should get summary data between passed range 1`] = `
+Object {
+  "endTime": 289960729.717,
+  "idle": 0.6339998841285706,
+  "other": 4.653000295162201,
+  "painting": 34.8999999165535,
+  "rendering": 425.89399832487106,
+  "scripting": 208.0020015835762,
+  "startTime": 289960055.634,
+}
+`;
+
+exports[`getSummary should not throw error on second call of getSummary 1`] = `
+Object {
+  "endTime": 289961229.717,
+  "idle": 52.38300037384033,
+  "other": 9.896000564098358,
+  "painting": 69.94999980926514,
+  "rendering": 847.373997092247,
+  "scripting": 394.4800021648407,
+  "startTime": 289959855.634,
+}
+`;
+
+exports[`getWarningCounts should get warning counts 1`] = `
 Object {
   "ForcedLayout": 4683,
   "ForcedStyle": 4684,
@@ -119,15 +143,3 @@ Object {
   },
 }
 `;
-
-exports[`should get summary data between passed range 1`] = `
-Object {
-  "endTime": 289960729.717,
-  "idle": 0.6339998841285706,
-  "other": 4.653000295162201,
-  "painting": 34.8999999165535,
-  "rendering": 425.89399832487106,
-  "scripting": 208.0020015835762,
-  "startTime": 289960055.634,
-}
-`;

tests/index.test.ts

@@ -1,61 +1,71 @@
 import Tracelib from '../src/index'
 import JANK_TRACE_LOG from './__fixtures__/jankTraceLog.json'
 
+let trace: Tracelib
+beforeAll(() => {
+    trace = new Tracelib(JANK_TRACE_LOG)
+})
+
 test('should contain traceLog', () => {
     const sampleTrace = new Tracelib({ foo: 'bar' })
     expect(sampleTrace.tracelog).toEqual({ foo: 'bar' })
 })
 
 test('should get FPS', () => {
-    const trace = new Tracelib(JANK_TRACE_LOG)
     const result = trace.getFPS()
     expect(result).toMatchSnapshot()
 })
 
-test('getSummary: should get summary data', () => {
-    const trace = new Tracelib(JANK_TRACE_LOG)
-    const result = trace.getSummary()
-    expect(result).toMatchSnapshot()
-})
+describe('getSummary', () => {
+    it('should get summary data', () => {
+        const result = trace.getSummary()
+        expect(result).toMatchSnapshot()
+    })
 
-test('getSummary: should throw error if main track is missing', () => {
-    const trace = new Tracelib([])
-    expect(() => trace.getSummary())
-        .toThrow(new Error('MainTrack is missing in traceLog'))
-})
+    it('should not throw error on second call of getSummary', () => {
+        const result = trace.getSummary()
+        expect(result).toMatchSnapshot()
+    })
 
-test('should get summary data between passed range', () => {
-    const trace = new Tracelib(JANK_TRACE_LOG)
-    const result = trace.getSummary(289960055.634, 289960729.717)
-    expect(result).toMatchSnapshot()
-})
+    it('should throw error if main track is missing', () => {
+        const tracelib = new Tracelib([])
+        expect(() => tracelib.getSummary())
+            .toThrow(new Error('MainTrack is missing in traceLog'))
+    })
 
-test('getWarningCounts: should get warning counts', () => {
-    const trace = new Tracelib(JANK_TRACE_LOG)
-    const result = trace.getWarningCounts()
-    expect(result).toMatchSnapshot()
+    it('should get summary data between passed range', () => {
+        const result = trace.getSummary(289960055.634, 289960729.717)
+        expect(result).toMatchSnapshot()
+    })
 })
 
-test('getWarningCounts: should throw error if main track is missing', () => {
-    const trace = new Tracelib([])
-    expect(() => trace.getWarningCounts())
-        .toThrow(new Error('MainTrack is missing in traceLog'))
+describe('getWarningCounts', () => {
+    it('should get warning counts', () => {
+        const result = trace.getWarningCounts()
+        expect(result).toMatchSnapshot()
+    })
+
+    it('should throw error if main track is missing', () => {
+        const tracelib = new Tracelib([])
+        expect(() => tracelib.getWarningCounts())
+            .toThrow(new Error('MainTrack is missing in traceLog'))
+    })
 })
 
 test('should get memory counters', () => {
-    const trace = new Tracelib(JANK_TRACE_LOG)
     const result = trace.getMemoryCounters()
     expect(result).toMatchSnapshot()
 })
 
-test('mainTrackEvents: should get events', () => {
-    const trace = new Tracelib(JANK_TRACE_LOG)
-    const result = trace.getMainTrackEvents()
-    expect(result.length).toEqual(56244)
-})
+describe('mainTrackEvents', () => {
+    it('should get events', () => {
+        const result = trace.getMainTrackEvents()
+        expect(result.length).toEqual(56244)
+    })
 
-test('mainTrackEvents: should throws error if main track is missing', () => {
-    const trace = new Tracelib([])
-    expect(() => trace.getMainTrackEvents())
-        .toThrow(new Error('MainTrack is missing in traceLog'))
-})
+    it('should throws error if main track is missing', () => {
+        const tracelib = new Tracelib([])
+        expect(() => tracelib.getMainTrackEvents())
+            .toThrow(new Error('MainTrack is missing in traceLog'))
+    })
+})