testsuite: move Go code to top-level folder

As described in https://golang.org/cmd/cgo/ ,
Cgo only notices changes to .c and .h files in the
same folder.

Move the testsuite to the top-level folder to get rid of
the manual cache cleaning which made running the tests
so much slower.

golang/go#24355

Author: rfjakob

Makefile

@@ -81,7 +81,4 @@ format: earlyoom
 	clang-format -i *.h *.c
 
 test: earlyoom
-# Go does not notice when the C code changes, so we have to
-# use `go clean` and `go test -a`.
-# See https://github.com/golang/go/issues/24355 .
-	cd tests && go clean -cache -testcache . && go test -a -v
+	go test -v

tests/c_wrappers.go renamed to testsuite_c_wrappers.go

@@ -1,15 +1,14 @@
-package tests
+package earlyoom_testsuite
 
 import (
 	"fmt"
 	"os"
 )
 
-// #cgo CFLAGS: -std=gnu99
-// #include "../globals.c"
-// #include "../sanitize.c"
-// #include "../msg.c"
-// #include "../meminfo.c"
+// #cgo CFLAGS: -std=gnu99 -DCGO
+// #include "meminfo.h"
+// #include "kill.h"
+// #include "msg.h"
 import "C"
 
 func sanitize(s string) string {

tests/cli_test.go renamed to testsuite_cli_test.go

@@ -1,4 +1,4 @@
-package tests
+package earlyoom_testsuite
 
 import (
 	"fmt"
@@ -154,7 +154,7 @@ func TestCli(t *testing.T) {
 }
 
 func TestRss(t *testing.T) {
-	cmd := exec.Command("../earlyoom")
+	cmd := exec.Command(earlyoomBinary)
 	err := cmd.Start()
 	if err != nil {
 		t.Fatal(err)

tests/helpers.go renamed to testsuite_helpers.go

@@ -1,4 +1,4 @@
-package tests
+package earlyoom_testsuite
 
 import (
 	"bytes"
@@ -16,10 +16,12 @@ type exitVals struct {
 	stderr string
 }
 
+const earlyoomBinary = "./earlyoom"
+
 // runEarlyoom runs earlyoom with a timeout
 func runEarlyoom(t *testing.T, args ...string) exitVals {
 	var stdoutBuf, stderrBuf bytes.Buffer
-	cmd := exec.Command("../earlyoom", args...)
+	cmd := exec.Command(earlyoomBinary, args...)
 	cmd.Stdout = &stdoutBuf
 	cmd.Stderr = &stderrBuf
 

tests/unit_test.go renamed to testsuite_unit_test.go

@@ -1,4 +1,4 @@
-package tests
+package earlyoom_testsuite
 
 import (
 	"os"