add testing.FailNow and related function to unreachable check (#711)

Signed-off-by: Abirdcfly <fp544037857@gmail.com>

rule/unreachable-code.go

@@ -16,6 +16,11 @@ func (*UnreachableCodeRule) Apply(file *lint.File, _ lint.Arguments) []lint.Fail
 		failures = append(failures, failure)
 	}
 
+	testingFunctions := map[string]bool{
+		"Fatal":   true,
+		"Fatalf":  true,
+		"FailNow": true,
+	}
 	branchingFunctions := map[string]map[string]bool{
 		"os": {"Exit": true},
 		"log": {
@@ -26,6 +31,9 @@ func (*UnreachableCodeRule) Apply(file *lint.File, _ lint.Arguments) []lint.Fail
 			"Panicf":  true,
 			"Panicln": true,
 		},
+		"t": testingFunctions,
+		"b": testingFunctions,
+		"f": testingFunctions,
 	}
 
 	w := lintUnreachableCode{onFailure, branchingFunctions}

testdata/unreachable-code.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"testing"
 )
 
 func foo() int {
@@ -35,3 +36,25 @@ func g() {
 
 	fmt.Println("Bye, playground")
 }
+
+func TestA(t *testing.T) {
+	tests := make([]int, 100)
+	for i := range tests {
+		println("i: ", i)
+		if i == 0 {
+			t.Fatal("i == 0") // MATCH /unreachable code after this statement/
+			println("unreachable")
+			continue
+		}
+		if i == 1 {
+			t.Fatalf("i:%d", i) // MATCH /unreachable code after this statement/
+			println("unreachable")
+			continue
+		}
+		if i == 2 {
+			t.FailNow() // MATCH /unreachable code after this statement/
+			println("unreachable")
+			continue
+		}
+	}
+}