output.txt

go test -parallel=1 -race -v parallel_test.go
=== RUN   TestOne
=== PAUSE TestOne
=== RUN   TestTwo
=== PAUSE TestTwo
=== CONT  TestTwo
=== CONT  TestOne
--- PASS: TestTwo (0.00s)
--- PASS: TestOne (0.00s)
PASS
ok  	command-line-arguments	1.020s

go test -parallel=2 -race -v parallel_test.go
=== RUN   TestOne
=== PAUSE TestOne
=== RUN   TestTwo
=== PAUSE TestTwo
=== CONT  TestTwo
=== CONT  TestOne
==================
WARNING: DATA RACE
Write at 0x00c420088240 by goroutine 6:
  runtime.mapassign_faststr()
      /Users/vasko/code/go/src/runtime/hashmap_fast.go:534 +0x0
  command-line-arguments.TestOne()
      /Users/vasko/tmp/parallel_test.go:9 +0x91
  testing.tRunner()
      /Users/vasko/code/go/src/testing/testing.go:769 +0x169

Previous write at 0x00c420088240 by goroutine 7:
  runtime.mapassign_faststr()
      /Users/vasko/code/go/src/runtime/hashmap_fast.go:534 +0x0
  command-line-arguments.TestTwo()
      /Users/vasko/tmp/parallel_test.go:20 +0x91
  testing.tRunner()
      /Users/vasko/code/go/src/testing/testing.go:769 +0x169

Goroutine 6 (running) created at:
  testing.(*T).Run()
      /Users/vasko/code/go/src/testing/testing.go:812 +0x535
  testing.runTests.func1()
      /Users/vasko/code/go/src/testing/testing.go:1036 +0xa4
  testing.tRunner()
      /Users/vasko/code/go/src/testing/testing.go:769 +0x169
  testing.runTests()
      /Users/vasko/code/go/src/testing/testing.go:1034 +0x4c7
  testing.(*M).Run()
      /Users/vasko/code/go/src/testing/testing.go:954 +0x271
  main.main()
      b001/_testmain.go:44 +0x228

Goroutine 7 (running) created at:
  testing.(*T).Run()
      /Users/vasko/code/go/src/testing/testing.go:812 +0x535
  testing.runTests.func1()
      /Users/vasko/code/go/src/testing/testing.go:1036 +0xa4
  testing.tRunner()
      /Users/vasko/code/go/src/testing/testing.go:769 +0x169
  testing.runTests()
      /Users/vasko/code/go/src/testing/testing.go:1034 +0x4c7
  testing.(*M).Run()
      /Users/vasko/code/go/src/testing/testing.go:954 +0x271
  main.main()
      b001/_testmain.go:44 +0x228
==================
==================
WARNING: DATA RACE
Write at 0x00c4200c2088 by goroutine 6:
  command-line-arguments.TestOne()
      /Users/vasko/tmp/parallel_test.go:9 +0xa4
  testing.tRunner()
      /Users/vasko/code/go/src/testing/testing.go:769 +0x169

Previous write at 0x00c4200c2088 by goroutine 7:
  command-line-arguments.TestTwo()
      /Users/vasko/tmp/parallel_test.go:20 +0xa4
  testing.tRunner()
      /Users/vasko/code/go/src/testing/testing.go:769 +0x169

Goroutine 6 (running) created at:
  testing.(*T).Run()
      /Users/vasko/code/go/src/testing/testing.go:812 +0x535
  testing.runTests.func1()
      /Users/vasko/code/go/src/testing/testing.go:1036 +0xa4
  testing.tRunner()
      /Users/vasko/code/go/src/testing/testing.go:769 +0x169
  testing.runTests()
      /Users/vasko/code/go/src/testing/testing.go:1034 +0x4c7
  testing.(*M).Run()
      /Users/vasko/code/go/src/testing/testing.go:954 +0x271
  main.main()
      b001/_testmain.go:44 +0x228

Goroutine 7 (running) created at:
  testing.(*T).Run()
      /Users/vasko/code/go/src/testing/testing.go:812 +0x535
  testing.runTests.func1()
      /Users/vasko/code/go/src/testing/testing.go:1036 +0xa4
  testing.tRunner()
      /Users/vasko/code/go/src/testing/testing.go:769 +0x169
  testing.runTests()
      /Users/vasko/code/go/src/testing/testing.go:1034 +0x4c7
  testing.(*M).Run()
      /Users/vasko/code/go/src/testing/testing.go:954 +0x271
  main.main()
      b001/_testmain.go:44 +0x228
==================
--- FAIL: TestOne (0.00s)
	testing.go:722: race detected during execution of test
--- FAIL: TestTwo (0.00s)
FAIL
exit status 1
FAIL	command-line-arguments	0.018s

parallel_test.go

package main

import "testing"

var data = make(map[string]string)

func TestOne(t *testing.T) {
	t.Parallel()
	data["foo"] = "bar"
	if len(data) != 1 {
		t.Error("Data map should have 1 entry")
	}
	if v, exists := data["foo"]; !exists || v != "bar" {
		t.Errorf("Value should have been 'bar' but instead found %s\n", v)
	}
}

func TestTwo(t *testing.T) {
	t.Parallel()
	data["foo"] = "baz"
	if len(data) != 1 {
		t.Error("Data map should have 1 entry")
	}
	if v, exists := data["foo"]; !exists || v != "baz" {
		t.Errorf("Value should have been 'baz' but instead found %s\n", v)
	}
}