The `system()` function executes the given shell command or raw command
vector, optionally terminating the spawned process after the specified
timeout.

Throws an exception if a timeout is specified but not a valid positive
integer value.

Throws an exception if the command argument is neither an array nor a
string value.

Throws an exception if an empty command vector is given.

Returns the exit code of the invoked process.

-- Testcase --
{%
	// When passing the command as string, `/bin/sh -c` is invoked with
	// the given command string as second argument
	system('x=1; echo $((x + x))');

	// When passing the command as array, the first value is taken as
	// executable to invoke and any further item as argument to the
	// invoked program. Internally `execvp()` is used, which means that
	// the executable path may be relative in which case it is looked
	// up in the directories specified by `$PATH`. Any array items are
	// implicitly stringified.
	system([ '/bin/sh', TESTFILES_PATH + '/testscripts/hello.sh', true, 0x42, 123.456000, { some: "dict" } ]);

	// By specifying a timeout, maximum execution time is limited to
	// that many milliseconds. If the program does not finish before the
	// timeout occurs, it is forcibly terminated with SIGKILL.
	system([ '/bin/sh', TESTFILES_PATH + '/testscripts/sleep.sh' ], 100);

	// The return value of system() is the exit code of the invoked program.
	let rc = system([ '/bin/sh', TESTFILES_PATH + '/testscripts/exit.sh' ]);

	printf("Return value is %d\n", rc);
%}
-- End --

-- File testscripts/hello.sh --
#!/bin/sh

echo "This is our test program running!"
echo "My arguments are:"

for arg in "$@"; do
	echo "<$arg>"
done
-- End --

-- File testscripts/sleep.sh --
#!/bin/sh

echo "I'll sleep for 10s now..."
sleep 10
echo "I am done sleeping."
-- End --

-- File testscripts/exit.sh --
#!/bin/sh

echo "I'll exit with code 5 now."
exit 5
-- End --

-- Expect stdout --
2
This is our test program running!
My arguments are:
<true>
<66>
<123.456>
<{ "some": "dict" }>
I'll sleep for 10s now...
I'll exit with code 5 now.
Return value is 5
-- End --


Passing an invalid command value throws an exception.

-- Testcase --
{%
	system(true);
%}
-- End --

-- Expect stderr --
Type error: Passed command is neither string nor array
In line 2, byte 13:

 `    system(true);`
  Near here -----^


-- End --

-- Testcase --
{%
	system([]);
%}
-- End --

-- Expect stderr --
Type error: Passed command array is empty
In line 2, byte 11:

 `    system([]);`
  Near here ---^


-- End --


Passing an invalid timeout throws an exception.

-- Testcase --
{%
	system("exit 0", "invalid")
%}
-- End --

-- Expect stderr --
Type error: Invalid timeout specified
In line 2, byte 28:

 `    system("exit 0", "invalid")`
  Near here --------------------^


-- End --

-- Testcase --
{%
	system("exit 0", -100)
%}
-- End --

-- Expect stderr --
Type error: Invalid timeout specified
In line 2, byte 23:

 `    system("exit 0", -100)`
  Near here ---------------^


-- End --