Reduce dependencies on common code in test cases

This reduces the amount of dependencies on code in the dbhub.io/common
module in the test cases. The only remaining place where it is used is
for the diff function. Eventually this should also be reworked so we can
completely eliminate the import of the common module and have an
independent test here (i.e. not asking the server to do something, then
calling server code to verify its behaviour).

Author: MKleusberg

dbhub_test.go

@@ -5,10 +5,12 @@ import (
 	"crypto/tls"
 	"io"
 	"log"
+	"math/rand"
 	"net/http"
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 
 	"github.com/docker/docker/pkg/fileutils"
 	sqlite "github.com/gwenn/gosqlite"
@@ -193,7 +195,7 @@ func TestDiff(t *testing.T) {
 	})
 
 	// Copy the database file to a temp location so we can make some changes
-	newFile := filepath.Join(t.TempDir(), "diff-"+common.RandomString(8)+".sqlite")
+	newFile := filepath.Join(t.TempDir(), "diff-"+randomString(8)+".sqlite")
 	_, err = fileutils.CopyFile(dbFile, newFile)
 	if err != nil {
 		t.Error(err)
@@ -270,7 +272,7 @@ func TestDiff(t *testing.T) {
 	assert.Len(t, diffs.Diff, 1)
 	assert.Equal(t, "foo", diffs.Diff[0].ObjectName)
 	assert.Equal(t, "table", diffs.Diff[0].ObjectType)
-	assert.Equal(t, common.DiffType("add"), diffs.Diff[0].Schema.ActionType)
+	assert.Equal(t, DiffType("add"), diffs.Diff[0].Schema.ActionType)
 	assert.Equal(t, "CREATE TABLE foo (first integer);", diffs.Diff[0].Schema.Sql)
 	assert.Equal(t, "", diffs.Diff[0].Schema.Before)
 	assert.Equal(t, "CREATE TABLE foo (first integer)", diffs.Diff[0].Schema.After)
@@ -288,7 +290,7 @@ func TestDiff(t *testing.T) {
 	assert.Len(t, diffs.Diff, 1)
 	assert.Equal(t, "foo", diffs.Diff[0].ObjectName)
 	assert.Equal(t, "table", diffs.Diff[0].ObjectType)
-	assert.Equal(t, common.DiffType("add"), diffs.Diff[0].Schema.ActionType)
+	assert.Equal(t, DiffType("add"), diffs.Diff[0].Schema.ActionType)
 	assert.Equal(t, "CREATE TABLE foo (first integer);", diffs.Diff[0].Schema.Sql)
 	assert.Equal(t, "", diffs.Diff[0].Schema.Before)
 	assert.Equal(t, "CREATE TABLE foo (first integer)", diffs.Diff[0].Schema.After)
@@ -306,7 +308,7 @@ func TestDiff(t *testing.T) {
 	assert.Len(t, diffs.Diff, 1)
 	assert.Equal(t, "foo", diffs.Diff[0].ObjectName)
 	assert.Equal(t, "table", diffs.Diff[0].ObjectType)
-	assert.Equal(t, common.DiffType("add"), diffs.Diff[0].Schema.ActionType)
+	assert.Equal(t, DiffType("add"), diffs.Diff[0].Schema.ActionType)
 	assert.Equal(t, "", diffs.Diff[0].Schema.Sql)
 	assert.Equal(t, "", diffs.Diff[0].Schema.Before)
 	assert.Equal(t, "CREATE TABLE foo (first integer)", diffs.Diff[0].Schema.After)
@@ -572,7 +574,7 @@ func TestUploadLive(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	dbB := filepath.Join(t.TempDir(), "diff-"+common.RandomString(8)+".sqlite")
+	dbB := filepath.Join(t.TempDir(), "diff-"+randomString(8)+".sqlite")
 	err = os.WriteFile(dbB, data, 0750)
 	if err != nil {
 		t.Error(err)
@@ -617,6 +619,17 @@ func TestWebpage(t *testing.T) {
 	assert.Equal(t, "https://docker-dev.dbhub.io:9443/default/Assembly Election 2017.sqlite", pageData.WebPage)
 }
 
+// randomString generates a random alphanumeric string of the desired length
+func randomString(length int) string {
+	rand.Seed(time.Now().UnixNano())
+	const alphaNum = "abcdefghijklmnopqrstuvwxyz0123456789"
+	randomString := make([]byte, length)
+	for i := range randomString {
+		randomString[i] = alphaNum[rand.Intn(len(alphaNum))]
+	}
+	return string(randomString)
+}
+
 // serverConnection is a utility function that sets up the API connection object to the test server, ready for use
 func serverConnection(apiKey string) Connection {
 	// Create a new DBHub.io API object