feat(e2e): add interactive TTY mode with expectrl for stdin testing

Add support for interactive TTY mode in e2e test runner using expectrl
crate. This enables tests to simulate interactive stdin input through
a PTY pseudo-terminal.

Key changes:
- Modified Step enum: `stdin: Str` → `interactive: bool`
- Added run_interactive_step function using sync expectrl with spawn_blocking
- Implemented [write-stdin:...] protocol for writing to stdin
- Empty content [write-stdin:] signals EOF (sends Ctrl-D)
- Updated stdin-passthrough fixture to use new protocol
- Created echo-stdin.js script that verifies TTY mode

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: branchseer

Cargo.lock

@@ -63,6 +63,7 @@ derive_more = "2.0.1"
 diff-struct = "0.5.3"
 directories = "6.0.0"
 elf = { version = "0.8.0", default-features = false }
+expectrl = "0.8.0"
 flate2 = "1.0.35"
 fspy = { path = "crates/fspy" }
 fspy_detours_sys = { path = "crates/fspy_detours_sys" }

Cargo.toml

@@ -24,6 +24,7 @@ which = { workspace = true }
 [dev-dependencies]
 copy_dir = { workspace = true }
 cow-utils = { workspace = true }
+expectrl = { workspace = true }
 insta = { workspace = true, features = ["glob", "json", "redactions", "filters", "ron"] }
 regex = { workspace = true }
 serde = { workspace = true, features = ["derive", "rc"] }

crates/vite_task_bin/Cargo.toml

@@ -0,0 +1,22 @@
+// Use writeSync to avoid buffering issues
+const fs = require('fs');
+
+// First, verify we're running in a TTY (should print "true" when using expectrl PTY)
+fs.writeSync(1, 'TTY: ' + String(process.stdin.isTTY) + '\n');
+
+// Signal the test runner to write "hello from stdin" to our stdin
+fs.writeSync(1, '[write-stdin:hello from stdin]');
+
+// Signal that we're done with stdin commands (this triggers EOF handling)
+fs.writeSync(1, '[write-stdin:]');
+
+// Read stdin asynchronously - the test runner will send data then EOF
+process.stdin.setEncoding('utf8');
+process.stdin.once('readable', () => {
+  const chunk = process.stdin.read();
+  if (chunk !== null) {
+    fs.writeSync(1, chunk);
+  }
+  fs.writeSync(1, 'Done\n');
+  process.exit(0);
+});

crates/vite_task_bin/tests/e2e_snapshots/fixtures/stdin-passthrough/echo-stdin.js

@@ -1,6 +1,3 @@
 {
-  "name": "stdin-passthrough",
-  "scripts": {
-    "echo-stdin": "node -e \"process.stdin.pipe(process.stdout)\""
-  }
+  "name": "stdin-passthrough"
 }

crates/vite_task_bin/tests/e2e_snapshots/fixtures/stdin-passthrough/package.json

@@ -1,7 +1,7 @@
-# Tests that stdin is passed through to tasks
+# Tests that stdin is passed through to tasks with interactive TTY
 
 [[e2e]]
 name = "stdin passthrough to single task"
 steps = [
-  { cmd = "vite run echo-stdin", stdin = "hello from stdin" },
+  { cmd = "vite run echo-stdin", interactive = true },
 ]

crates/vite_task_bin/tests/e2e_snapshots/fixtures/stdin-passthrough/snapshots.toml

@@ -1,12 +1,16 @@
 ---
 source: crates/vite_task_bin/tests/e2e_snapshots/main.rs
-assertion_line: 203
 expression: e2e_outputs
 input_file: crates/vite_task_bin/tests/e2e_snapshots/fixtures/stdin-passthrough
 ---
 > vite run echo-stdin
-$ node -e "process.stdin.pipe(process.stdout)"
-hello from stdin
+$ node echo-stdin.js
+TTY: true
+$ node echo-stdin.js
+TTY: true
+[write-stdin:hello from stdin][write-stdin:]hello from stdin
+Done
+
 
 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
     Vite+ Task Runner • Execution Summary
@@ -17,6 +21,6 @@ Performance:  0% cache hit rate
 
 Task Details:
 ────────────────────────────────────────────────
-  [1] stdin-passthrough#echo-stdin: $ node -e "process.stdin.pipe(process.stdout)" ✓
+  [1] stdin-passthrough#echo-stdin: $ node echo-stdin.js ✓
       → Cache miss: no previous cache entry found
 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

crates/vite_task_bin/tests/e2e_snapshots/fixtures/stdin-passthrough/snapshots/stdin passthrough to single task.snap

@@ -0,0 +1,7 @@
+{
+  "tasks": {
+    "echo-stdin": {
+      "command": "node echo-stdin.js"
+    }
+  }
+}