headless_lms_models/

course_instances.rs

use std::collections::HashMap;

use crate::{
    chapters,
    chapters::DatabaseChapter,
    exercises,
    prelude::*,
    user_details::UserDetail,
    users::{self, User},
};

#[derive(Debug, Serialize, Deserialize, PartialEq, Clone)]
#[cfg_attr(feature = "ts_rs", derive(TS))]
pub struct CourseInstance {
    pub id: Uuid,
    pub created_at: DateTime<Utc>,
    pub updated_at: DateTime<Utc>,
    pub deleted_at: Option<DateTime<Utc>>,
    pub course_id: Uuid,
    pub starts_at: Option<DateTime<Utc>>,
    pub ends_at: Option<DateTime<Utc>>,
    pub name: Option<String>,
    pub description: Option<String>,
    pub teacher_in_charge_name: String,
    pub teacher_in_charge_email: String,
    pub support_email: Option<String>,
}

impl CourseInstance {
    pub fn is_open(&self) -> bool {
        self.starts_at.map(|sa| sa < Utc::now()).unwrap_or_default()
    }
}

#[derive(Debug, Deserialize)]
#[cfg_attr(feature = "ts_rs", derive(TS))]
pub struct CourseInstanceForm {
    pub name: Option<String>,
    pub description: Option<String>,
    pub teacher_in_charge_name: String,
    pub teacher_in_charge_email: String,
    pub support_email: Option<String>,
    pub opening_time: Option<DateTime<Utc>>,
    pub closing_time: Option<DateTime<Utc>>,
}

#[derive(Debug, Clone, Copy)]
pub struct NewCourseInstance<'a> {
    pub course_id: Uuid,
    pub name: Option<&'a str>,
    pub description: Option<&'a str>,
    pub teacher_in_charge_name: &'a str,
    pub teacher_in_charge_email: &'a str,
    pub support_email: Option<&'a str>,
    pub opening_time: Option<DateTime<Utc>>,
    pub closing_time: Option<DateTime<Utc>>,
}

pub async fn insert(
    conn: &mut PgConnection,
    pkey_policy: PKeyPolicy<Uuid>,
    new_course_instance: NewCourseInstance<'_>,
) -> ModelResult<CourseInstance> {
    let course_instance = sqlx::query_as!(
        CourseInstance,
        r#"
INSERT INTO course_instances (
    id,
    course_id,
    name,
    description,
    teacher_in_charge_name,
    teacher_in_charge_email,
    support_email
  )
VALUES ($1, $2, $3, $4, $5, $6, $7)
RETURNING id,
  created_at,
  updated_at,
  deleted_at,
  course_id,
  starts_at,
  ends_at,
  name,
  description,
  teacher_in_charge_name,
  teacher_in_charge_email,
  support_email
"#,
        pkey_policy.into_uuid(),
        new_course_instance.course_id,
        new_course_instance.name,
        new_course_instance.description,
        new_course_instance.teacher_in_charge_name,
        new_course_instance.teacher_in_charge_email,
        new_course_instance.support_email,
    )
    .fetch_one(conn)
    .await?;
    Ok(course_instance)
}

pub async fn get_course_instance(
    conn: &mut PgConnection,
    course_instance_id: Uuid,
) -> ModelResult<CourseInstance> {
    let course_instance = sqlx::query_as!(
        CourseInstance,
        r#"
SELECT id,
  created_at,
  updated_at,
  deleted_at,
  course_id,
  starts_at,
  ends_at,
  name,
  description,
  teacher_in_charge_name,
  teacher_in_charge_email,
  support_email
FROM course_instances
WHERE id = $1
  AND deleted_at IS NULL;
    "#,
        course_instance_id,
    )
    .fetch_one(conn)
    .await?;
    Ok(course_instance)
}

pub async fn get_course_instance_with_info(
    conn: &mut PgConnection,
    course_instance_id: Uuid,
) -> ModelResult<CourseInstanceWithCourseInfo> {
    let course_instance = sqlx::query_as!(
        CourseInstanceWithCourseInfo,
        r#"
SELECT
    c.id AS course_id,
    c.slug AS course_slug,
    c.name AS course_name,
    c.description AS course_description,
    ci.id AS course_instance_id,
    ci.name AS course_instance_name,
    ci.description AS course_instance_description,
    o.name AS organization_name
FROM course_instances AS ci
  LEFT JOIN courses AS c ON ci.course_id = c.id
  LEFT JOIN organizations AS o ON o.id = c.organization_id
WHERE ci.id = $1
  AND ci.deleted_at IS NULL
  AND c.deleted_at IS NULL
  AND o.deleted_at IS NULL
    "#,
        course_instance_id,
    )
    .fetch_one(conn)
    .await?;
    Ok(course_instance)
}

pub async fn get_default_by_course_id(
    conn: &mut PgConnection,
    course_id: Uuid,
) -> ModelResult<CourseInstance> {
    let res = sqlx::query_as!(
        CourseInstance,
        "
SELECT *
FROM course_instances
WHERE course_id = $1
  AND name IS NULL
  AND deleted_at IS NULL
    ",
        course_id
    )
    .fetch_one(conn)
    .await?;
    Ok(res)
}

pub async fn get_organization_id(
    conn: &mut PgConnection,
    course_instance_id: Uuid,
) -> ModelResult<Uuid> {
    let res = sqlx::query!(
        "
SELECT courses.organization_id
FROM course_instances
  JOIN courses ON courses.id = course_instances.course_id
WHERE course_instances.id = $1
",
        course_instance_id
    )
    .fetch_one(conn)
    .await?;
    Ok(res.organization_id)
}

pub async fn current_course_instance_of_user(
    conn: &mut PgConnection,
    user_id: Uuid,
    course_id: Uuid,
) -> ModelResult<Option<CourseInstance>> {
    let course_instance_enrollment = sqlx::query_as!(
        CourseInstance,
        r#"
SELECT i.id,
  i.created_at,
  i.updated_at,
  i.deleted_at,
  i.course_id,
  i.starts_at,
  i.ends_at,
  i.name,
  i.description,
  i.teacher_in_charge_name,
  i.teacher_in_charge_email,
  i.support_email
FROM user_course_settings ucs
  JOIN course_instances i ON (ucs.current_course_instance_id = i.id)
WHERE ucs.user_id = $1
  AND ucs.current_course_id = $2
  AND ucs.deleted_at IS NULL;
    "#,
        user_id,
        course_id,
    )
    .fetch_optional(conn)
    .await?;
    Ok(course_instance_enrollment)
}

pub async fn course_instance_by_users_latest_enrollment(
    conn: &mut PgConnection,
    user_id: Uuid,
    course_id: Uuid,
) -> ModelResult<Option<CourseInstance>> {
    let course_instance = sqlx::query_as!(
        CourseInstance,
        r#"
SELECT i.id,
  i.created_at,
  i.updated_at,
  i.deleted_at,
  i.course_id,
  i.starts_at,
  i.ends_at,
  i.name,
  i.description,
  i.teacher_in_charge_name,
  i.teacher_in_charge_email,
  i.support_email
FROM course_instances i
  JOIN course_instance_enrollments ie ON (i.id = ie.course_id)
WHERE i.course_id = $1
  AND i.deleted_at IS NULL
  AND ie.user_id = $2
  AND ie.deleted_at IS NULL
ORDER BY ie.created_at DESC;
    "#,
        course_id,
        user_id,
    )
    .fetch_optional(conn)
    .await?;
    Ok(course_instance)
}

pub async fn get_all_course_instances(conn: &mut PgConnection) -> ModelResult<Vec<CourseInstance>> {
    let course_instances = sqlx::query_as!(
        CourseInstance,
        r#"
SELECT id,
  created_at,
  updated_at,
  deleted_at,
  course_id,
  starts_at,
  ends_at,
  name,
  description,
  teacher_in_charge_name,
  teacher_in_charge_email,
  support_email
FROM course_instances
WHERE deleted_at IS NULL
"#
    )
    .fetch_all(conn)
    .await?;
    Ok(course_instances)
}

pub async fn get_course_instances_for_course(
    conn: &mut PgConnection,
    course_id: Uuid,
) -> ModelResult<Vec<CourseInstance>> {
    let course_instances = sqlx::query_as!(
        CourseInstance,
        r#"
SELECT id,
  created_at,
  updated_at,
  deleted_at,
  course_id,
  starts_at,
  ends_at,
  name,
  description,
  teacher_in_charge_name,
  teacher_in_charge_email,
  support_email
FROM course_instances
WHERE course_id = $1
  AND deleted_at IS NULL;
        "#,
        course_id,
    )
    .fetch_all(conn)
    .await?;
    Ok(course_instances)
}

pub async fn get_course_instance_ids_with_course_id(
    conn: &mut PgConnection,
    course_id: Uuid,
) -> ModelResult<Vec<Uuid>> {
    let res = sqlx::query!(
        r#"
SELECT id
FROM course_instances
WHERE course_id = $1
  AND deleted_at IS NULL;
        "#,
        course_id,
    )
    .map(|r| r.id)
    .fetch_all(conn)
    .await?;
    Ok(res)
}

#[derive(Debug, Serialize)]
#[cfg_attr(feature = "ts_rs", derive(TS))]
pub struct ChapterScore {
    #[serde(flatten)]
    pub chapter: DatabaseChapter,
    pub score_given: f32,
    pub score_total: i32,
}

#[derive(Debug, Default, Serialize)]
#[cfg_attr(feature = "ts_rs", derive(TS))]
pub struct PointMap(pub HashMap<Uuid, f32>);

#[derive(Debug, Serialize)]
#[cfg_attr(feature = "ts_rs", derive(TS))]
pub struct Points {
    pub chapter_points: Vec<ChapterScore>,
    pub users: Vec<UserDetail>,
    // PointMap is a workaround for https://github.com/rhys-vdw/ts-auto-guard/issues/158
    pub user_chapter_points: HashMap<Uuid, PointMap>,
}

pub async fn get_points(
    conn: &mut PgConnection,
    instance_id: Uuid,
    _pagination: Pagination, // TODO
) -> ModelResult<Points> {
    let mut chapter_point_totals = HashMap::<Uuid, i32>::new();
    let mut exercise_to_chapter_id = HashMap::new();
    let course_instance = crate::course_instances::get_course_instance(conn, instance_id).await?;
    let exercises =
        exercises::get_exercises_by_course_id(&mut *conn, course_instance.course_id).await?;
    for exercise in exercises {
        if let Some(chapter_id) = exercise.chapter_id {
            // exercises without chapter ids (i.e. exams) are not counted
            let total = chapter_point_totals.entry(chapter_id).or_default();
            *total += exercise.score_maximum;
            exercise_to_chapter_id.insert(exercise.id, chapter_id);
        }
    }

    let users: HashMap<Uuid, User> =
        users::get_users_by_course_instance_enrollment(conn, instance_id)
            .await?
            .into_iter()
            .map(|u| (u.id, u))
            .collect();
    let mut chapter_points_given = HashMap::<Uuid, f32>::new();
    let states = sqlx::query!(
        "
SELECT user_id,
  exercise_id,
  score_given
FROM user_exercise_states
WHERE course_id = $1
  AND deleted_at IS NULL
ORDER BY user_id ASC
",
        course_instance.course_id,
    )
    .fetch_all(&mut *conn)
    .await?;
    let mut user_chapter_points = HashMap::<Uuid, PointMap>::new();
    for state in states {
        let user = match users.get(&state.user_id) {
            Some(user) => user,
            None => {
                tracing::warn!(
                    "user {} has an exercise state but no enrollment",
                    state.user_id
                );
                continue;
            }
        };
        if let Some(chapter_id) = exercise_to_chapter_id.get(&state.exercise_id).copied() {
            let chapter_points = user_chapter_points.entry(user.id).or_default();
            let user_given = chapter_points.0.entry(chapter_id).or_default();
            let chapter_given = chapter_points_given.entry(chapter_id).or_default();
            let score_given = state.score_given.unwrap_or_default();
            *user_given += score_given;
            *chapter_given += score_given;
        }
    }

    let chapters = chapters::course_instance_chapters(&mut *conn, instance_id).await?;
    let mut chapter_points: Vec<ChapterScore> = chapters
        .into_iter()
        .map(|c| ChapterScore {
            score_given: chapter_points_given.get(&c.id).copied().unwrap_or_default(),
            score_total: chapter_point_totals.get(&c.id).copied().unwrap_or_default(),
            chapter: c,
        })
        .collect();
    chapter_points.sort_by_key(|c| c.chapter.chapter_number);

    let list_of_users = users.into_values().collect::<Vec<_>>();
    let user_id_to_details =
        crate::user_details::get_users_details_by_user_id_map(&mut *conn, &list_of_users).await?;

    Ok(Points {
        chapter_points,
        users: list_of_users
            .into_iter()
            .filter_map(|user| user_id_to_details.get(&user.id).cloned())
            .collect::<Vec<_>>(),
        user_chapter_points,
    })
}

pub async fn edit(
    conn: &mut PgConnection,
    instance_id: Uuid,
    update: CourseInstanceForm,
) -> ModelResult<()> {
    sqlx::query!(
        "
UPDATE course_instances
SET name = $1,
  description = $2,
  teacher_in_charge_name = $3,
  teacher_in_charge_email = $4,
  support_email = $5,
  starts_at = $6,
  ends_at = $7
WHERE id = $8
",
        update.name,
        update.description,
        update.teacher_in_charge_name,
        update.teacher_in_charge_email,
        update.support_email,
        update.opening_time,
        update.closing_time,
        instance_id
    )
    .execute(conn)
    .await?;
    Ok(())
}

pub async fn delete(conn: &mut PgConnection, id: Uuid) -> ModelResult<()> {
    sqlx::query!(
        "
UPDATE course_instances
SET deleted_at = now()
WHERE id = $1
AND deleted_at IS NULL
",
        id
    )
    .execute(conn)
    .await?;
    Ok(())
}

pub async fn get_course_id(conn: &mut PgConnection, id: Uuid) -> ModelResult<Uuid> {
    let res = sqlx::query!(
        "
SELECT course_id
FROM course_instances
WHERE id = $1
",
        id
    )
    .fetch_one(conn)
    .await?;
    Ok(res.course_id)
}

pub async fn is_open(conn: &mut PgConnection, id: Uuid) -> ModelResult<bool> {
    let res = sqlx::query!(
        "
SELECT starts_at,
  ends_at
FROM course_instances
WHERE id = $1
",
        id
    )
    .fetch_one(conn)
    .await?;
    let has_started = match res.starts_at {
        Some(starts_at) => starts_at <= Utc::now(),
        None => true,
    };
    let has_ended = match res.ends_at {
        Some(ends_at) => ends_at <= Utc::now(),
        None => false,
    };
    let is_open = has_started && !has_ended;
    Ok(is_open)
}

pub async fn get_by_ids(
    conn: &mut PgConnection,
    course_instance_ids: &[Uuid],
) -> ModelResult<Vec<CourseInstance>> {
    let course_instances = sqlx::query_as!(
        CourseInstance,
        r#"
SELECT *
FROM course_instances
WHERE id IN (SELECT * FROM UNNEST($1::uuid[]))
    "#,
        course_instance_ids
    )
    .fetch_all(conn)
    .await?;
    Ok(course_instances)
}

pub struct CourseInstanceWithCourseInfo {
    pub course_id: Uuid,
    pub course_slug: String,
    pub course_name: String,
    pub course_description: Option<String>,
    pub course_instance_id: Uuid,
    pub course_instance_name: Option<String>,
    pub course_instance_description: Option<String>,
    pub organization_name: String,
}

pub async fn get_enrolled_course_instances_for_user(
    conn: &mut PgConnection,
    user_id: Uuid,
) -> ModelResult<Vec<CourseInstanceWithCourseInfo>> {
    let course_instances = sqlx::query_as!(
        CourseInstanceWithCourseInfo,
        r#"
SELECT
    c.id AS course_id,
    c.slug AS course_slug,
    c.name AS course_name,
    c.description AS course_description,
    ci.id AS course_instance_id,
    ci.name AS course_instance_name,
    ci.description AS course_instance_description,
    o.name AS organization_name
FROM course_instances AS ci
  JOIN course_instance_enrollments AS cie ON ci.id = cie.course_instance_id
  LEFT JOIN courses AS c ON ci.course_id = c.id
  LEFT JOIN organizations AS o ON o.id = c.organization_id
WHERE cie.user_id = $1
  AND ci.deleted_at IS NULL
  AND cie.deleted_at IS NULL
  AND c.deleted_at IS NULL
  AND o.deleted_at IS NULL
"#,
        user_id
    )
    .fetch_all(conn)
    .await?;
    Ok(course_instances)
}

pub async fn get_enrolled_course_instances_for_user_with_exercise_type(
    conn: &mut PgConnection,
    user_id: Uuid,
    exercise_type: &str,
) -> ModelResult<Vec<CourseInstanceWithCourseInfo>> {
    let course_instances = sqlx::query_as!(
        CourseInstanceWithCourseInfo,
        r#"
SELECT DISTINCT ON (ci.id)
    c.id AS course_id,
    c.slug AS course_slug,
    c.name AS course_name,
    c.description AS course_description,
    ci.id AS course_instance_id,
    ci.name AS course_instance_name,
    ci.description AS course_instance_description,
    o.name AS organization_name
FROM course_instances AS ci
  JOIN course_instance_enrollments AS cie ON ci.id = cie.course_instance_id
  LEFT JOIN courses AS c ON ci.course_id = c.id
  LEFT JOIN exercises AS e ON e.course_id = c.id
  LEFT JOIN exercise_slides AS es ON es.exercise_id = e.id
  LEFT JOIN exercise_tasks AS et ON et.exercise_slide_id = es.id
  LEFT JOIN organizations AS o ON o.id = c.organization_id
WHERE cie.user_id = $1
  AND et.exercise_type = $2
  AND ci.deleted_at IS NULL
  AND cie.deleted_at IS NULL
  AND c.deleted_at IS NULL
  AND e.deleted_at IS NULL
  AND es.deleted_at IS NULL
  AND et.deleted_at IS NULL
"#,
        user_id,
        exercise_type,
    )
    .fetch_all(conn)
    .await?;
    Ok(course_instances)
}

/// Deletes submissions, peer reviews, points and etc. for a course and user. Main purpose is for teachers who are testing their course with their own accounts.
pub async fn reset_progress_on_course_instance_for_user(
    conn: &mut PgConnection,
    user_id: Uuid,
    course_id: Uuid,
) -> ModelResult<()> {
    let mut tx = conn.begin().await?;
    sqlx::query!(
        "
UPDATE exercise_slide_submissions
SET deleted_at = now()
WHERE user_id = $1
  AND course_id = $2
  AND deleted_at IS NULL
  ",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE exercise_task_submissions
SET deleted_at = now()
WHERE exercise_slide_submission_id IN (
    SELECT id
    FROM exercise_slide_submissions
    WHERE user_id = $1
      AND course_id = $2
  )
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE peer_review_queue_entries
SET deleted_at = now()
WHERE user_id = $1
  AND course_id = $2
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE peer_or_self_review_submissions
SET deleted_at = now()
WHERE user_id = $1
  AND course_id = $2
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE peer_or_self_review_question_submissions
SET deleted_at = now()
WHERE peer_or_self_review_submission_id IN (
    SELECT id
    FROM peer_or_self_review_submissions
    WHERE user_id = $1
      AND course_id = $2
  )
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE exercise_task_gradings
SET deleted_at = now()
WHERE exercise_task_submission_id IN (
    SELECT id
    FROM exercise_task_submissions
    WHERE exercise_slide_submission_id IN (
        SELECT id
        FROM exercise_slide_submissions
        WHERE user_id = $1
          AND course_id = $2
      )
  )
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;

    sqlx::query!(
        "
UPDATE user_exercise_states
SET deleted_at = now()
WHERE user_id = $1
  AND course_id = $2
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE user_exercise_task_states
SET deleted_at = now()
WHERE user_exercise_slide_state_id IN (
    SELECT id
    FROM user_exercise_slide_states
    WHERE user_exercise_state_id IN (
        SELECT id
        FROM user_exercise_states
        WHERE user_id = $1
          AND course_id = $2
      )
  )
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE user_exercise_slide_states
SET deleted_at = now()
WHERE user_exercise_state_id IN (
    SELECT id
    FROM user_exercise_states
    WHERE user_id = $1
      AND course_id = $2
  )
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE teacher_grading_decisions
SET deleted_at = now()
WHERE user_exercise_state_id IN (
    SELECT id
    FROM user_exercise_states
    WHERE user_id = $1
      AND course_id = $2
  )
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE course_module_completions
SET deleted_at = now()
WHERE user_id = $1
AND course_id = $2
AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;
    sqlx::query!(
        "
UPDATE generated_certificates
SET deleted_at = NOW()
WHERE user_id = $1
  AND certificate_configuration_id IN (
    SELECT certificate_configuration_id
    FROM certificate_configuration_to_requirements
    WHERE course_module_id IN (
        SELECT id
        FROM course_modules
        WHERE course_id = $2
      )
      AND deleted_at IS NULL
  )
  AND deleted_at IS NULL
",
        user_id,
        course_id
    )
    .execute(&mut *tx)
    .await?;

    tx.commit().await?;
    Ok(())
}

pub async fn get_course_average_duration(
    conn: &mut PgConnection,
    course_id: Uuid,
) -> ModelResult<Option<i64>> {
    let res = sqlx::query!(
        "
SELECT AVG(
    EXTRACT(
      EPOCH
      FROM cmc.completion_date - ce.created_at
    )
  )::int8 AS average_duration_seconds
FROM course_instance_enrollments ce
  JOIN course_module_completions cmc ON (
    cmc.course_id = ce.course_id
    AND cmc.user_id = ce.user_id
  )
WHERE ce.course_id = $1
  AND ce.deleted_at IS NULL
  AND cmc.deleted_at IS NULL;
        ",
        course_id
    )
    .fetch_optional(conn)
    .await?;

    Ok(res.map(|r| r.average_duration_seconds).unwrap_or_default())
}

pub async fn get_student_duration(
    conn: &mut PgConnection,
    user_id: Uuid,
    course_id: Uuid,
) -> ModelResult<Option<i64>> {
    let res = sqlx::query!(
        "
SELECT COALESCE(
    EXTRACT(
      EPOCH
      FROM cmc.completion_date - ce.created_at
    )::int8,
    0
  ) AS student_duration_seconds
FROM course_instance_enrollments ce
  JOIN course_module_completions cmc ON (
    cmc.course_id = ce.course_id
    AND cmc.user_id = ce.user_id
  )
WHERE ce.course_id = $1
  AND ce.user_id = $2
  AND ce.deleted_at IS NULL
  AND cmc.deleted_at IS NULL;
        ",
        course_id,
        user_id
    )
    .fetch_optional(conn)
    .await?;

    Ok(res.map(|r| r.student_duration_seconds).unwrap_or_default())
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::{
        course_instance_enrollments::NewCourseInstanceEnrollment, exercise_tasks::NewExerciseTask,
        test_helper::*,
    };

    #[tokio::test]
    async fn allows_only_one_instance_per_course_without_name() {
        insert_data!(:tx, :user, :org, course: course_id);

        let mut tx1 = tx.begin().await;
        // courses always have a default instance with no name, so this should fail
        let mut instance = NewCourseInstance {
            course_id,
            name: None,
            description: None,
            teacher_in_charge_name: "teacher",
            teacher_in_charge_email: "teacher@example.com",
            support_email: None,
            opening_time: None,
            closing_time: None,
        };
        insert(tx1.as_mut(), PKeyPolicy::Generate, instance)
            .await
            .unwrap_err();
        tx1.rollback().await;

        let mut tx2 = tx.begin().await;
        // after we give it a name, it should be ok
        instance.name = Some("name");
        insert(tx2.as_mut(), PKeyPolicy::Generate, instance)
            .await
            .unwrap();
    }

    #[tokio::test]
    async fn gets_enrolled_course_instances_for_user_with_exercise_type() {
        insert_data!(:tx, user:user_id, :org, course:course_id, :instance, course_module:_course_module_id, chapter:chapter_id, page:page_id, :exercise, slide:exercise_slide_id);

        // enroll user on course
        crate::course_instance_enrollments::insert_enrollment_and_set_as_current(
            tx.as_mut(),
            NewCourseInstanceEnrollment {
                course_id,
                user_id,
                course_instance_id: instance.id,
            },
        )
        .await
        .unwrap();
        let course_instances =
            get_enrolled_course_instances_for_user_with_exercise_type(tx.as_mut(), user_id, "tmc")
                .await
                .unwrap();
        assert!(
            course_instances.is_empty(),
            "user should not be enrolled on any course with tmc exercises"
        );

        // insert tmc exercise task
        crate::exercise_tasks::insert(
            tx.as_mut(),
            PKeyPolicy::Generate,
            NewExerciseTask {
                assignment: Vec::new(),
                exercise_slide_id,
                exercise_type: "tmc".to_string(),
                model_solution_spec: None,
                private_spec: None,
                public_spec: None,
                order_number: 1,
            },
        )
        .await
        .unwrap();
        let course_instances =
            get_enrolled_course_instances_for_user_with_exercise_type(tx.as_mut(), user_id, "tmc")
                .await
                .unwrap();
        assert_eq!(
            course_instances.len(),
            1,
            "user should be enrolled on one course with tmc exercises"
        );
        tx.rollback().await;
    }

    #[tokio::test]
    async fn gets_course_average_duration_with_empty_database() {
        insert_data!(:tx, :user, :org, :course);
        let duration = get_course_average_duration(tx.as_mut(), course)
            .await
            .unwrap();
        assert!(duration.is_none())
    }
}