[MM-18193] Use vendor folder when compiling test plugins (#12188)

build/Jenkinsfile.pr

@@ -416,4 +416,4 @@ pipeline {
 			cleanWs notFailBuild: true
 		}
 	}
-}
+}

build/README.md

@@ -14,6 +14,6 @@ We have a docker image to build `mattermost-server` and it is based on Go docker
 
 In our Docker Hub Repository we have the following images:
 
-- `mattermost/mattermost-build-server:dec-7-2018` which is based on Go 1.11 you can use for MM versions <= `5.9.0`
-- `mattermost/mattermost-build-server:feb-28-2019` which is based on Go 1.12 you can use for MM versions > `5.9.0` <= `5.15.0`
+- `mattermost/mattermost-build-server:dec-7-2018` which is based on Go 1.11 you can use for MM versions <= `5.8.0`
+- `mattermost/mattermost-build-server:feb-28-2019` which is based on Go 1.12 you can use for MM versions >= `5.9.0` <= `5.15.0`
 - `mattermost/mattermost-build-server:sep-17-2019` which is based on Go 1.12.9 you can use for MM versions >= `5.16.0`

utils/test_files_compiler.go

@@ -5,11 +5,11 @@ package utils
 
 import (
 	"bytes"
-	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -38,23 +38,13 @@ func CompileGo(t *testing.T, sourceCode, outputPath string) {
 	err = ioutil.WriteFile(main, []byte(sourceCode), 0600)
 	require.NoError(t, err)
 
-	if os.Getenv("GO111MODULE") != "off" {
-		var mattermostServerPath string
-
-		// Generate a go.mod file relying on the local copy of the mattermost-server.
-		// testlib linked mattermost-server into the general temporary directory for this test.
-		mattermostServerPath, err = filepath.Abs("mattermost-server")
-		require.NoError(t, err)
-
-		goMod(t, dir, "init", "mattermost.com/test")
-		goMod(t, dir, "edit", "-require", "github.com/mattermost/mattermost-server@v0.0.0")
-		goMod(t, dir, "edit", "-replace", fmt.Sprintf("github.com/mattermost/mattermost-server@v0.0.0=%s", mattermostServerPath))
-		goMod(t, dir, "edit", "-replace", fmt.Sprintf("git.apache.org/thrift.git=%s", "github.com/apache/thrift@v0.0.0-20180902110319-2566ecd5d999"))
-	}
+	_, sourceFile, _, ok := runtime.Caller(0)
+	require.True(t, ok)
+	serverPath := filepath.Dir(filepath.Dir(sourceFile))
 
 	out := &bytes.Buffer{}
-	cmd := exec.Command("go", "build", "-o", outputPath, "main.go")
-	cmd.Dir = dir
+	cmd := exec.Command("go", "build", "-mod=vendor", "-o", outputPath, main)
+	cmd.Dir = serverPath
 	cmd.Stdout = out
 	cmd.Stderr = out
 	err = cmd.Run()