add fail_test.go to test CI

fail_test.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"sync"
+	"testing"
+)
+
+func TestFail(t *testing.T) {
+	if testing.Short() {
+		t.Skip()
+	}
+	t.Fatal("fake failure")
+}
+
+func TestRace(t *testing.T) {
+	var v int
+	var wg sync.WaitGroup
+	wg.Add(100)
+	for i := 0; i < 100; i++ {
+		go func() {
+			defer wg.Done()
+			v++
+			v--
+		}()
+	}
+	wg.Wait()
+	t.Log(v)
+}
+
+func TestLint(t *testing.T) {
+	const UnusedVar = 1 // lint should complain for unused variable
+	const ALL_CAPS = 10 // should be AllCaps
+	err := os.ErrNotExist
+	if err == os.ErrNotExist { // should use errors.Is
+		err := errors.New("fake error") // shadowed variable
+		t.Log(err)
+	}
+}