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|
use super::{ContextError, Store};
use miette::Result;
use sqlite::Connection;
pub struct SQLiteStore {
location: String,
connection: Option<Connection>,
}
impl SQLiteStore {
/// Wrap connection in a Result to make it easier to unwrap later
fn get_connection(&self) -> Result<&Connection, sqlite::Error> {
match &self.connection {
Some(conn) => Ok(conn),
None => Err(sqlite::Error {
code: None,
message: Some("Uninitialized".into()),
}),
}
}
fn create_table(&mut self) -> Result<(), sqlite::Error> {
let conn = self.get_connection()?;
let mut statement = conn.prepare("CREATE TABLE RATAT ( COUNTER SMALLINT )")?;
statement.next()?;
Ok(())
}
fn insert_counter(&mut self, counter: i64) -> Result<(), sqlite::Error> {
let conn = self.get_connection()?;
let mut statement = conn.prepare("INSERT INTO RATAT ( COUNTER ) VALUES ( :counter )")?;
statement.bind((":counter", counter))?;
statement.next()?;
Ok(())
}
fn select_counter(&self) -> Result<i64, sqlite::Error> {
let conn = self.get_connection()?;
let mut statement = conn.prepare("SELECT COUNTER FROM RATAT")?;
statement.next()?;
statement.read("COUNTER")
}
fn update_counter(&mut self, counter: i64) -> Result<(), sqlite::Error> {
let conn = self.get_connection()?;
let mut statement = conn.prepare("UPDATE RATAT SET COUNTER = :counter")?;
statement.bind((":counter", counter))?;
statement.next()?;
Ok(())
}
}
impl Default for SQLiteStore {
fn default() -> Self {
SQLiteStore {
location: ":memory:".into(),
connection: Option::None,
}
}
}
impl Store for SQLiteStore {
/// Init SQLite for counting. Creates `RATAT` table with single row, with
/// counter set to `0`
fn init(&mut self) -> Result<(), ContextError> {
let conn_path = self.location.clone();
let conn = sqlite::open(conn_path)?;
self.connection = Option::Some(conn);
self.create_table()?;
self.insert_counter(0)?;
Ok(())
}
/// Selects counter from `RATAT` table. Since sqlite doesn't scrutinize the
/// value and we have a more restricted datatype (i64 -> u8), we use
/// `try_from` which may produce an error result.
fn get_counter(&self) -> Result<u8, ContextError> {
let result = self.select_counter()?;
let count = u8::try_from(result)?;
Ok(count)
}
/// Updates row with counter value on `RATAT` table
fn set_counter(&mut self, new_count: u8) -> Result<u8, ContextError> {
self.update_counter(i64::from(new_count))?;
Ok(new_count)
}
}
#[cfg(test)]
mod tests {
use super::*;
// Practically, the `Store` trait is what we interface with externally, and
// provides the more general `Result` interface we want to work with so
// that's what we test here
#[test]
fn default() {
let context = SQLiteStore::default();
assert_eq!(context.location, ":memory:");
assert!(context.connection.is_none());
}
#[test]
fn init() {
let mut context = SQLiteStore::default();
let res = context.init();
assert!(res.is_ok());
assert!(context.connection.is_some());
}
#[test]
fn get_counter() {
let mut context = SQLiteStore::default();
assert!(context.init().is_ok());
let res = context.get_counter();
assert!(res.is_ok());
assert_eq!(res.unwrap(), 0);
}
#[test]
fn get_counter_error() {
let context = SQLiteStore::default();
// don't initialize
let res = context.get_counter();
assert!(res.is_err());
}
#[test]
fn get_counter_outside_range() {
let mut context = SQLiteStore::default();
assert!(context.init().is_ok());
let new_value = -1;
if let Some(conn) = &context.connection {
let mut statement = conn.prepare("UPDATE RATAT SET COUNTER = ?").unwrap();
statement.bind((1, new_value)).unwrap();
statement.next().unwrap();
}
let res = context.get_counter();
assert!(res.is_err());
}
#[test]
fn set_counter() {
let mut context = SQLiteStore::default();
assert!(context.init().is_ok());
let expected = 240;
let res = context.set_counter(expected);
assert!(res.is_ok());
assert_eq!(res.unwrap(), expected);
}
#[test]
fn set_counter_error() {
let mut context = SQLiteStore::default();
// don't initialize
let res = context.set_counter(1);
assert!(res.is_err());
}
#[test]
fn set_and_get() {
let mut context = SQLiteStore::default();
assert!(context.init().is_ok());
let count_0 = context.get_counter().unwrap();
assert_eq!(count_0, 0);
let new_num = 244;
let res = context.set_counter(new_num);
assert!(res.is_ok());
assert_eq!(res.unwrap(), new_num);
let count_1 = context.get_counter().unwrap();
assert_eq!(count_1, new_num);
assert_ne!(count_0, count_1);
}
}
|
