//! Test command for checking the IL verifier.
//!
//! The `test verifier` test command looks for annotations on instructions like this:
//!
//!     jump ebb3 ; error: jump to non-existent EBB
//!
//! This annotation means that the verifier is expected to given an error for the jump instruction
//! containing the substring "jump to non-existent EBB".

use std::borrow::{Borrow, Cow};
use cretonne::verify_function;
use cretonne::ir::Function;
use cton_reader::TestCommand;
use filetest::subtest::{SubTest, Context, Result};
use utils::match_directive;

struct TestVerifier;

pub fn subtest(parsed: &TestCommand) -> Result<Box<SubTest>> {
    assert_eq!(parsed.command, "verifier");
    if !parsed.options.is_empty() {
        Err(format!("No options allowed on {}", parsed))
    } else {
        Ok(Box::new(TestVerifier))
    }
}

impl SubTest for TestVerifier {
    fn name(&self) -> Cow<str> {
        Cow::from("verifier")
    }

    fn needs_verifier(&self) -> bool {
        // Running the verifier before this test would defeat its purpose.
        false
    }

    fn run(&self, func: Cow<Function>, context: &Context) -> Result<()> {
        let func = func.borrow();

        // Scan source annotations for "error:" directives.
        let mut expected = None;
        for comment in &context.details.comments {
            if let Some(tail) = match_directive(comment.text, "error:") {
                // Currently, the verifier can only report one problem at a time.
                // Reject more than one `error:` directives.
                if expected.is_some() {
                    return Err("cannot handle multiple error: directives".to_string());
                }
                expected = Some((comment.entity, tail));
            }
        }

        match verify_function(func) {
            Ok(_) => {
                match expected {
                    None => Ok(()),
                    Some((_, msg)) => Err(format!("passed, expected error: {}", msg)),
                }
            }
            Err(got) => {
                match expected {
                    None => Err(format!("verifier pass, got {}", got)),
                    Some((want_loc, want_msg)) if got.message.contains(want_msg) => {
                        if want_loc == got.location {
                            Ok(())
                        } else {
                            Err(format!("correct error reported on {}, but wanted {}",
                                        got.location,
                                        want_loc))
                        }
                    }
                    Some(_) => Err(format!("mismatching error: {}", got)),
                }
            }
        }
    }
}