Add --sql-preconnect CLI flag for PostgreSQL startup connections (#21035)

Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: jarred-sumner-bot <220441119+jarred-sumner-bot@users.noreply.github.com>
Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>
Co-authored-by: Jarred-Sumner <709451+Jarred-Sumner@users.noreply.github.com>

test/cli/run/sql-preconnect.test.ts

@@ -0,0 +1,84 @@
+import { describe, expect, test } from "bun:test";
+import { bunEnv, bunExe, tempDirWithFiles } from "harness";
+
+describe("--sql-preconnect", () => {
+  test("should attempt to preconnect to PostgreSQL on startup", async () => {
+    let connectionAttempts = 0;
+    const { promise, resolve } = Promise.withResolvers<void>();
+
+    await using server = Bun.listen({
+      port: 0,
+      hostname: "127.0.0.1",
+      socket: {
+        open(socket) {
+          connectionAttempts++;
+          socket.end();
+          if (connectionAttempts >= 1) {
+            resolve();
+          }
+        },
+        data() {},
+        close() {},
+      },
+    });
+
+    const testDir = tempDirWithFiles("sql-preconnect-test", {
+      "index.js": `console.log("Script executed");`,
+    });
+
+    const proc = Bun.spawn({
+      cmd: [bunExe(), "--sql-preconnect", "index.js"],
+      env: {
+        ...bunEnv,
+        DATABASE_URL: `postgres://127.0.0.1:${server.port}/MY_DATABASE`,
+      },
+      cwd: testDir,
+    });
+
+    await promise;
+    proc.kill();
+    await proc.exited;
+
+    expect(connectionAttempts).toBeGreaterThan(0);
+  });
+
+  test("should not connect when flag is not used", async () => {
+    let connectionAttempts = 0;
+
+    await using server = Bun.listen({
+      port: 0,
+      hostname: "127.0.0.1",
+      socket: {
+        open(socket) {
+          connectionAttempts++;
+          socket.end();
+        },
+        data() {},
+        close() {},
+      },
+    });
+
+    const testDir = tempDirWithFiles("sql-no-preconnect", {
+      "index.js": `console.log("Normal script executed");`,
+    });
+
+    await using proc = Bun.spawn({
+      cmd: [bunExe(), "index.js"],
+      env: {
+        ...bunEnv,
+        DATABASE_URL: `postgres://127.0.0.1:${server.port}/MY_DATABASE`,
+      },
+      cwd: testDir,
+    });
+
+    const [stdout, stderr, exitCode] = await Promise.all([
+      new Response(proc.stdout).text(),
+      new Response(proc.stderr).text(),
+      proc.exited,
+    ]);
+
+    expect(exitCode).toBe(0);
+    expect(stdout).toContain("Normal script executed");
+    expect(connectionAttempts).toBe(0); // No connection should be attempted without the flag
+  });
+});