server var tests

enginetest/server_engine_test.go

@@ -375,3 +375,88 @@ func TestServerPreparedStatements(t *testing.T) {
 		})
 	}
 }
+
+func TestServerQueries(t *testing.T) {
+	port, perr := findEmptyPort()
+	require.NoError(t, perr)
+
+	s, serr := initTestServer(port)
+	require.NoError(t, serr)
+
+	go s.Start()
+	defer s.Close()
+
+	tests := []serverScriptTest{
+		{
+			name:  "test that config variables are properly set",
+			setup: []string{},
+			assertions: []serverScriptTestAssertion{
+				{
+					query: "select @@hostname, @@port",
+					//query:  "select @@hostname, @@port, @@max_connections",
+					isExec: false,
+					expectedRows: []any{
+						sql.Row{"macbook.local", port},
+					},
+					checkRows: func(t *testing.T, rows *gosql.Rows, expectedRows []any) (bool, error) {
+						var resHostname string
+						var resPort int
+						var rowNum int
+						for rows.Next() {
+							if err := rows.Scan(&resHostname, &resPort); err != nil {
+								return false, err
+							}
+							if rowNum >= len(expectedRows) {
+								return false, nil
+							}
+							expectedRow := expectedRows[rowNum].(sql.Row)
+							require.Equal(t, expectedRow[0].(string), resHostname)
+							require.Equal(t, expectedRow[1].(int), resPort)
+						}
+						return true, nil
+					},
+				},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			conn, cerr := dbr.Open("mysql", fmt.Sprintf(noUserFmt, address, port), nil)
+			require.NoError(t, cerr)
+			defer conn.Close()
+			commonSetup := []string{
+				"create database test_db;",
+				"use test_db;",
+			}
+			commonTeardown := []string{
+				"drop database test_db",
+			}
+			for _, stmt := range append(commonSetup, test.setup...) {
+				_, err := conn.Exec(stmt)
+				require.NoError(t, err)
+			}
+			for _, assertion := range test.assertions {
+				t.Run(assertion.query, func(t *testing.T) {
+					if assertion.skip {
+						t.Skip()
+					}
+					rows, err := conn.Query(assertion.query, assertion.args...)
+					if assertion.expectErr {
+						require.Error(t, err)
+						return
+					}
+					require.NoError(t, err)
+
+					ok, err := assertion.checkRows(t, rows, assertion.expectedRows)
+					require.NoError(t, err)
+					require.True(t, ok)
+				})
+			}
+			for _, stmt := range append(commonTeardown) {
+				_, err := conn.Exec(stmt)
+				require.NoError(t, err)
+			}
+		})
+	}
+}

server/server.go

@@ -18,6 +18,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"os"
 	"strconv"
 	"time"
 
@@ -119,13 +120,38 @@ func portInUse(hostPort string) bool {
 	return false
 }
 
-func updateSystemVariables(cfg mysql.ListenerConfig) {
-	_, port, _ := net.SplitHostPort(cfg.Listener.Addr().String())
-	portInt, _ := strconv.ParseInt(port, 10, 64)
-	sql.SystemVariables.AssignValues(map[string]interface{}{
-		"max_connections": cfg.MaxConns,
-		"port":            portInt,
+func getHostname() (string, error) {
+	hostname, err := os.Hostname()
+	if err != nil {
+		return "", err
+	}
+	return hostname, nil
+}
+
+func updateSystemVariables(cfg mysql.ListenerConfig) error {
+	hostname, err := getHostname()
+	if err != nil {
+		return err
+	}
+	_, port, err := net.SplitHostPort(cfg.Listener.Addr().String())
+	if err != nil {
+		return err
+	}
+	portInt, err := strconv.ParseInt(port, 10, 64)
+	if err != nil {
+		return err
+	}
+	// TODO: add the rest of the config variables
+	err = sql.SystemVariables.AssignValues(map[string]interface{}{
+		"port":     portInt,
+		"hostname": hostname,
+		// TODO: this causes an error because max_connections is 0?
+		//"max_connections": cfg.MaxConns,
 	})
+	if err != nil {
+		return err
+	}
+	return nil
 }
 
 func newServerFromHandler(cfg Config, e *sqle.Engine, sm *SessionManager, handler mysql.Handler, sel ServerEventListener) (*Server, error) {
@@ -182,7 +208,10 @@ func newServerFromHandler(cfg Config, e *sqle.Engine, sm *SessionManager, handle
 		return nil, err
 	}
 
-	updateSystemVariables(listenerCfg)
+	err = updateSystemVariables(listenerCfg)
+	if err != nil {
+		return nil, err
+	}
 
 	return &Server{
 		Listener:   protocolListener,