fix: handle stopped Docker containers in test setup

The docker test helpers checked if a container existed via `docker
container inspect`, but this returns true for stopped/exited containers
too. When a container existed but wasn't running, the code skipped
creation and went straight to pinging — which timed out after 10s.

Extract an ensureContainer helper that:
1. Inspects the container state (not just existence)
2. Runs `docker start` if the container exists but is stopped
3. Creates via `docker run` if the container doesn't exist
4. Handles the race where a parallel test process creates the
   container between our inspect and run calls

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

https://claude.ai/code/session_01WLKDmB7kemgPsjsj9KFEXa

Author: claude

internal/sqltest/docker/enabled.go

@@ -3,6 +3,7 @@ package docker
 import (
 	"fmt"
 	"os/exec"
+	"strings"
 
 	"golang.org/x/sync/singleflight"
 )
@@ -15,3 +16,44 @@ func Installed() error {
 	}
 	return nil
 }
+
+// ensureContainer makes sure a Docker container with the given name is running.
+// It handles three cases:
+//  1. Container doesn't exist: create it with docker run
+//  2. Container exists but stopped: start it with docker start
+//  3. Container exists and running: do nothing
+//
+// It also handles the race condition where a parallel test process creates the
+// container between our inspect and run calls.
+func ensureContainer(name string, runArgs ...string) error {
+	// Check if container exists and whether it's running
+	output, err := exec.Command("docker", "container", "inspect",
+		"-f", "{{.State.Running}}", name).CombinedOutput()
+
+	if err == nil {
+		// Container exists — check if it's running
+		if strings.TrimSpace(string(output)) != "true" {
+			// Container exists but is stopped, start it
+			if startOut, startErr := exec.Command("docker", "start", name).CombinedOutput(); startErr != nil {
+				return fmt.Errorf("docker start %s: %s: %w", name, string(startOut), startErr)
+			}
+		}
+		return nil
+	}
+
+	// Container doesn't exist, create it
+	args := append([]string{"run", "--name", name}, runArgs...)
+	createOut, createErr := exec.Command("docker", args...).CombinedOutput()
+
+	if createErr != nil {
+		// Handle race: another process may have created the container between
+		// our inspect and run calls
+		conflictMsg := fmt.Sprintf(`Conflict. The container name "/%s" is already in use`, name)
+		if strings.Contains(string(createOut), conflictMsg) {
+			return nil
+		}
+		return fmt.Errorf("docker run %s: %s: %w", name, string(createOut), createErr)
+	}
+
+	return nil
+}

internal/sqltest/docker/mysql.go

@@ -5,7 +5,6 @@ import (
 	"database/sql"
 	"fmt"
 	"os/exec"
-	"strings"
 	"time"
 
 	_ "github.com/go-sql-driver/mysql"
@@ -46,30 +45,14 @@ func startMySQLServer(c context.Context) (string, error) {
 		}
 	}
 
-	var exists bool
-	{
-		cmd := exec.Command("docker", "container", "inspect", "sqlc_sqltest_docker_mysql")
-		// This means we've already started the container
-		exists = cmd.Run() == nil
-	}
-
-	if !exists {
-		cmd := exec.Command("docker", "run",
-			"--name", "sqlc_sqltest_docker_mysql",
-			"-e", "MYSQL_ROOT_PASSWORD=mysecretpassword",
-			"-e", "MYSQL_DATABASE=dinotest",
-			"-p", "3306:3306",
-			"-d",
-			"mysql:9",
-		)
-
-		output, err := cmd.CombinedOutput()
-		fmt.Println(string(output))
-
-		msg := `Conflict. The container name "/sqlc_sqltest_docker_mysql" is already in use by container`
-		if !strings.Contains(string(output), msg) && err != nil {
-			return "", err
-		}
+	if err := ensureContainer("sqlc_sqltest_docker_mysql",
+		"-e", "MYSQL_ROOT_PASSWORD=mysecretpassword",
+		"-e", "MYSQL_DATABASE=dinotest",
+		"-p", "3306:3306",
+		"-d",
+		"mysql:9",
+	); err != nil {
+		return "", err
 	}
 
 	ctx, cancel := context.WithTimeout(c, 10*time.Second)

internal/sqltest/docker/postgres.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"log/slog"
 	"os/exec"
-	"strings"
 	"time"
 
 	"github.com/jackc/pgx/v5"
@@ -48,31 +47,15 @@ func startPostgreSQLServer(c context.Context) (string, error) {
 
 	uri := "postgres://postgres:mysecretpassword@localhost:5432/postgres?sslmode=disable"
 
-	var exists bool
-	{
-		cmd := exec.Command("docker", "container", "inspect", "sqlc_sqltest_docker_postgres")
-		// This means we've already started the container
-		exists = cmd.Run() == nil
-	}
-
-	if !exists {
-		cmd := exec.Command("docker", "run",
-			"--name", "sqlc_sqltest_docker_postgres",
-			"-e", "POSTGRES_PASSWORD=mysecretpassword",
-			"-e", "POSTGRES_USER=postgres",
-			"-p", "5432:5432",
-			"-d",
-			"postgres:16",
-			"-c", "max_connections=200",
-		)
-
-		output, err := cmd.CombinedOutput()
-		fmt.Println(string(output))
-
-		msg := `Conflict. The container name "/sqlc_sqltest_docker_postgres" is already in use by container`
-		if !strings.Contains(string(output), msg) && err != nil {
-			return "", err
-		}
+	if err := ensureContainer("sqlc_sqltest_docker_postgres",
+		"-e", "POSTGRES_PASSWORD=mysecretpassword",
+		"-e", "POSTGRES_USER=postgres",
+		"-p", "5432:5432",
+		"-d",
+		"postgres:16",
+		"-c", "max_connections=200",
+	); err != nil {
+		return "", err
 	}
 
 	ctx, cancel := context.WithTimeout(c, 5*time.Second)