feat: add_user and user_exists with accompanying test suites

DESCRIPTION
    add_user
	Adds new user to DB. Implementers must ensure username
	uniqueness scoped at forge instance level. When applicable, HTML
	link to profile photo may be stored as we..
    user_exists
	Checks if a user exists in database. Optionally provide hostname
	of forge instance to get forge-specific results.

db/db-core/src/lib.rs

@@ -40,6 +40,7 @@ pub mod ops;
 #[cfg(feature = "test")]
 pub mod tests;
 
+use dev::*;
 pub use ops::GetConnection;
 
 pub mod prelude {
@@ -65,7 +66,20 @@ pub struct CreateForge<'a> {
     pub forge_type: ForgeImplementation,
 }
 
-use dev::*;
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+/// add new user to database
+pub struct AddUser<'a> {
+    /// hostname of the forge instance: with scheme but remove trailing slash
+    /// hostname can be derived  from html_link also, but used to link to user's forge instance
+    pub hostname: &'a str,
+    /// username of the user
+    pub username: &'a str,
+    /// html link to the user profile
+    pub html_link: &'a str,
+    /// OPTIONAL: html link to the user's profile photo
+    pub profile_photo: Option<&'a str>,
+}
+
 #[async_trait]
 /// Starchart's database requirements. To implement support for $Database, kindly implement this
 /// trait.
@@ -84,6 +98,13 @@ pub trait SCDatabase: std::marker::Send + std::marker::Sync + CloneSPDatabase {
 
     /// check if forge type exists
     async fn forge_type_exists(&self, forge_type: &ForgeImplementation) -> DBResult<bool>;
+
+    /// add new user to database
+    async fn add_user(&self, u: &AddUser) -> DBResult<()>;
+
+    /// check if an user exists. When hostname of a forge instace is provided, username search is
+    /// done only on that forge
+    async fn user_exists(&self, username: &str, hostname: Option<&str>) -> DBResult<bool>;
 }
 
 /// Trait to clone SCDatabase

db/db-core/src/tests.rs

@@ -19,13 +19,21 @@
 use crate::prelude::*;
 
 /// adding forge works
-pub async fn adding_forge_works<T: SCDatabase>(db: &T, create_forge_msg: CreateForge<'static>) {
+pub async fn adding_forge_works<T: SCDatabase>(
+    db: &T,
+    create_forge_msg: CreateForge<'static>,
+    add_user_msg: AddUser<'static>,
+    add_user_msg2: AddUser<'static>,
+) {
     let _ = db.delete_forge_instance(&create_forge_msg.hostname).await;
     db.create_forge_isntance(&create_forge_msg).await.unwrap();
     assert!(
         db.forge_exists(create_forge_msg.hostname).await.unwrap(),
         "forge creation failed, forge existance check failure"
     );
+
+    db.add_user(&add_user_msg).await.unwrap();
+    db.add_user(&add_user_msg2).await.unwrap();
 }
 
 /// test if all forge type implementations are loaded into DB