feat(tests, repl): add first repl test using pexpect

tests/repl/test.py

@@ -0,0 +1,53 @@
+import pexpect
+import sys
+import os
+
+
+def get_repl():
+    executable = None
+    for p in ["./arkscript", "cmake-build-debug/arkscript", "build/arkscript"]:
+        if os.path.exists(p):
+            executable = p
+            break
+    if executable is None:
+        print("Couldn't find a valid path to 'arkscript' executable")
+        sys.exit(1)
+
+    child = pexpect.spawn(executable, timeout=2, encoding="utf-8")
+    child.logfile = sys.stdout
+    return child
+
+
+def test(prompt: str, command: str, expected: str):
+    try:
+        repl.expect(prompt)
+        repl.send(command)
+        if expected is not None:
+            repl.expect(expected)
+    except pexpect.ExceptionPexpect:
+        print(f"Tried to match '{prompt}{command.strip()}' with '{expected}' but got {repl.after}")
+        raise
+
+
+repl = get_repl()
+
+# repl headers
+repl.expect(r"ArkScript REPL -- Version [0-9]+\.[0-9]+\.[0-9]+-[a-f0-9]{8} \[LICENSE: Mozilla Public License 2\.0\]")
+repl.expect(r"Type \"quit\" to quit\. Try \"help\" for more information")
+
+# completion
+test("main:001> ", "(le", "let")
+repl.send("t a 5)\r\n")
+
+test("main:002> ", "(print a)\r\n", "5")
+
+test("main:003> ", "(im", "port")
+repl.sendcontrol("c")
+
+test("main:003> ", "(let foo (fun (bar) (* bar 7))) (print (foo 7))\r\n", "49")
+
+test("main:004> ", "# just a comment\r\n", "main:005> ")
+
+if repl.isalive():
+    repl.sendline("quit")
+    repl.close()