Ability to mock behaviours for tests

src/mock_behaviour.rs

@@ -0,0 +1,155 @@
+//! This module provides ways to tweak mocked calendars, so that they can return errors on some tests
+
+use std::error::Error;
+
+/// This stores some behaviour tweaks, that describe how a mocked instance will behave during a given test
+///
+/// So that a functions fails _n_ times after _m_ initial successes, set `(m, n)` for the suited parameter
+#[derive(Default, Clone, Debug)]
+pub struct MockBehaviour {
+    /// If this is true, every action will be allowed
+    pub is_suspended: bool,
+
+    // From the CalDavSource trait
+    pub get_calendars_behaviour: (u32, u32),
+    //pub get_calendar_behaviour: (u32, u32),
+    pub create_calendar_behaviour: (u32, u32),
+
+    // From the BaseCalendar trait
+    pub add_item_behaviour: (u32, u32),
+
+    // From the DavCalendar trait
+    pub get_item_version_tags_behaviour: (u32, u32),
+    pub get_item_by_id_behaviour: (u32, u32),
+    pub delete_item_behaviour: (u32, u32),
+}
+
+impl MockBehaviour {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// All items will fail at once, for `n_fails` times
+    pub fn fail_now(n_fails: u32) -> Self {
+        Self {
+            is_suspended: false,
+            get_calendars_behaviour: (0, n_fails),
+            //get_calendar_behaviour: (0, n_fails),
+            create_calendar_behaviour: (0, n_fails),
+            add_item_behaviour: (0, n_fails),
+            get_item_version_tags_behaviour: (0, n_fails),
+            get_item_by_id_behaviour: (0, n_fails),
+            delete_item_behaviour: (0, n_fails),
+        }
+    }
+
+    /// Suspend this mock behaviour until you call `resume`
+    pub fn suspend(&mut self) {
+        self.is_suspended = true;
+    }
+    /// Make this behaviour active again
+    pub fn resume(&mut self) {
+        self.is_suspended = false;
+    }
+
+    pub fn copy_from(&mut self, other: &Self) {
+        self.get_calendars_behaviour = other.get_calendars_behaviour;
+        self.create_calendar_behaviour = other.create_calendar_behaviour;
+    }
+
+    pub fn can_get_calendars(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.is_suspended { return Ok(()) }
+        decrement(&mut self.get_calendars_behaviour, "get_calendars")
+    }
+    // pub fn can_get_calendar(&mut self) -> Result<(), Box<dyn Error>> {
+    //     if self.is_suspended { return Ok(()) }
+    //     decrement(&mut self.get_calendar_behaviour, "get_calendar")
+    // }
+    pub fn can_create_calendar(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.is_suspended { return Ok(()) }
+        decrement(&mut self.create_calendar_behaviour, "create_calendar")
+    }
+    pub fn can_add_item(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.is_suspended { return Ok(()) }
+        decrement(&mut self.add_item_behaviour, "add_item")
+    }
+    pub fn can_get_item_version_tags(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.is_suspended { return Ok(()) }
+        decrement(&mut self.get_item_version_tags_behaviour, "get_item_version_tags")
+    }
+    pub fn can_get_item_by_id(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.is_suspended { return Ok(()) }
+        decrement(&mut self.get_item_by_id_behaviour, "get_item_by_id")
+    }
+    pub fn can_delete_item(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.is_suspended { return Ok(()) }
+        decrement(&mut self.delete_item_behaviour, "delete_item")
+    }
+}
+
+
+/// Return Ok(()) in case the value is `(1+, _)` or `(_, 0)`, or return Err and decrement otherwise
+fn decrement(value: &mut (u32, u32), descr: &str) -> Result<(), Box<dyn Error>> {
+    let remaining_successes = value.0;
+    let remaining_failures = value.1;
+
+    if remaining_successes > 0 {
+        value.0 = value.0 - 1;
+        log::debug!("Mock behaviour: allowing a {} ({:?})", descr, value);
+        Ok(())
+    } else {
+        if remaining_failures > 0 {
+            value.1 = value.1 - 1;
+            log::debug!("Mock behaviour: failing a {} ({:?})", descr, value);
+            Err(format!("Mocked behaviour requires this {} to fail this time. ({:?})", descr, value).into())
+        } else {
+            log::debug!("Mock behaviour: allowing a {} ({:?})", descr, value);
+            Ok(())
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_mock_behaviour() {
+        let mut ok = MockBehaviour::new();
+        assert!(ok.can_get_calendars().is_ok());
+        assert!(ok.can_get_calendars().is_ok());
+        assert!(ok.can_get_calendars().is_ok());
+        assert!(ok.can_get_calendars().is_ok());
+        assert!(ok.can_get_calendars().is_ok());
+        assert!(ok.can_get_calendars().is_ok());
+        assert!(ok.can_get_calendars().is_ok());
+
+        let mut now = MockBehaviour::fail_now(2);
+        assert!(now.can_get_calendars().is_err());
+        assert!(now.can_create_calendar().is_err());
+        assert!(now.can_create_calendar().is_err());
+        assert!(now.can_get_calendars().is_err());
+        assert!(now.can_get_calendars().is_ok());
+        assert!(now.can_get_calendars().is_ok());
+        assert!(now.can_create_calendar().is_ok());
+
+        let mut custom = MockBehaviour{
+            get_calendars_behaviour: (0,1),
+            create_calendar_behaviour: (1,3),
+            ..MockBehaviour::default()
+        };
+        assert!(custom.can_get_calendars().is_err());
+        assert!(custom.can_get_calendars().is_ok());
+        assert!(custom.can_get_calendars().is_ok());
+        assert!(custom.can_get_calendars().is_ok());
+        assert!(custom.can_get_calendars().is_ok());
+        assert!(custom.can_get_calendars().is_ok());
+        assert!(custom.can_get_calendars().is_ok());
+        assert!(custom.can_create_calendar().is_ok());
+        assert!(custom.can_create_calendar().is_err());
+        assert!(custom.can_create_calendar().is_err());
+        assert!(custom.can_create_calendar().is_err());
+        assert!(custom.can_create_calendar().is_ok());
+        assert!(custom.can_create_calendar().is_ok());
+    }
+}