Add a test target for the shell

shell/Makefile

@@ -10,7 +10,9 @@ OBJS		= sh.o list.o
 
 main: $(OBJS)
 	$(CC) $(LDFLAGS) $(OBJS) -o $(OUT)
-	./sh
 
 clean:
 	rm -f *.o sh core out
+
+test: main
+	python3 shell-test.py $(OUT)

shell/shell-test.py

+import os
+import sys
+import subprocess
+import time
+import tempfile
+
+def run_command_through_shell(cmd, shellp, no_read=False) :
+    shellp.stdin.write(cmd)
+    shellp.stdin.flush()
+    if not no_read:
+        result = os.read(shellp.stdout.fileno(), 1000)
+        return result.decode('utf-8')
+    return None
+
+def create_shell_process(shell_exec) :
+    p = subprocess.Popen(shell_exec, universal_newlines=True, stdout=subprocess.PIPE,
+                        stdin=subprocess.PIPE, stderr=subprocess.STDOUT)
+    return p
+
+
+def expect(shellp, command, expected, min_time=None, max_time=None) :
+    if expected and type(expected) != set:
+        expected = {expected}
+
+    print("=" * 80)
+    print(f"CMD: {command}")
+    t0 = time.time()
+    r = run_command_through_shell(command, shellp, expected is None)
+    t1 = time.time()
+    print(f"RESULT: {r}")
+    if expected and r not in expected:
+        print(f"EXPECTED: {' OR '.join(expected)}")
+        print("FAIL")
+        return False
+    elif min_time and (t1 - t0) < min_time:
+        print(f"COMMAND FINISHED TOO FAST")
+        return False
+    elif max_time and (t1 - t0) > max_time:
+        print(f"TIME LIMIT EXCEEDED")
+        return False
+    else:
+        print("PASS")
+        return True
+
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        print(f"Run as f{sys.argv[0]} SHELL_EXEC")
+        exit(1)
+
+    shell_exec = os.path.abspath(sys.argv[1])
+    with tempfile.TemporaryDirectory() as tmpdir:
+        os.chdir(tmpdir)
+
+        # Create a process running the shell
+        p = create_shell_process(shell_exec)
+
+        # Push the following commands through the shell and
+        # check their output.
+        tests = [("/bin/pwd\n", tmpdir + "\n"),
+                 ("pwd\n", tmpdir + "\n"),
+                 ("touch file1.txt\n", None),
+                 ("ls\n", "file1.txt\n"),
+                 ("sleep 5; echo 'hello'\n", "hello\n", 4, 6),
+                 ("sleep 5 & echo 'hello'\n", "hello\n", 0, 1),
+                 ("echo line1 > file1.txt\n", None),
+                 ("cat < file1.txt\n", "line1\n"),
+                 ("cat file1.txt | wc -l\n", "1\n"),
+                 ("cat file1.txt | cat | cat | cat | cat | wc -l\n", "1\n"),
+                 ("echo 'x' | cat | wc -l & echo 2\n", {"1\n", "2\n"})
+                 ]
+
+        all_pass = True
+        for test in tests:
+            all_pass = expect(p, *test) and all_pass
+
+        # Send EOF to the shell
+        p.stdin.close()
+        # The shell should exit
+        p.wait()
+
+        print ("=" * 80)
+        if all_pass:
+            print ("PASS: All tests have passed.")
+        else:
+            print ("FAIL: Some tests have failed.")
+        print ("=" * 80)