Issue:
Bug: [FEATURE] Implement `AuthorizationInterface` for `MockDb`



Spin off from https://github.com/juspay/hyperswitch/issues/172. Refer to the parent issue for more information

Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
Implement AuthorizationInterface for MockDb


### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

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2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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## How did you test it?
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## Checklist
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- [ ] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed the submitted code
- [x] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Testing:

Patch:
diff --git a/crates/diesel_models/src/authorization.rs b/crates/diesel_models/src/authorization.rs
index 64fd1c65187..b6f75bbb9b7 100644
--- a/crates/diesel_models/src/authorization.rs
+++ b/crates/diesel_models/src/authorization.rs
@@ -57,6 +57,21 @@ pub struct AuthorizationUpdateInternal {
     pub connector_authorization_id: Option<String>,
 }
 
+impl AuthorizationUpdateInternal {
+    pub fn create_authorization(self, source: Authorization) -> Authorization {
+        Authorization {
+            status: self.status.unwrap_or(source.status),
+            error_code: self.error_code.or(source.error_code),
+            error_message: self.error_message.or(source.error_message),
+            modified_at: self.modified_at.unwrap_or(common_utils::date_time::now()),
+            connector_authorization_id: self
+                .connector_authorization_id
+                .or(source.connector_authorization_id),
+            ..source
+        }
+    }
+}
+
 impl From<AuthorizationUpdate> for AuthorizationUpdateInternal {
     fn from(authorization_child_update: AuthorizationUpdate) -> Self {
         let now = Some(common_utils::date_time::now());
diff --git a/crates/router/src/db/authorization.rs b/crates/router/src/db/authorization.rs
index f24daaf718a..d167d177537 100644
--- a/crates/router/src/db/authorization.rs
+++ b/crates/router/src/db/authorization.rs
@@ -1,3 +1,4 @@
+use diesel_models::authorization::AuthorizationUpdateInternal;
 use error_stack::IntoReport;
 
 use super::{MockDb, Store};
@@ -77,28 +78,71 @@ impl AuthorizationInterface for Store {
 impl AuthorizationInterface for MockDb {
     async fn insert_authorization(
         &self,
-        _authorization: storage::AuthorizationNew,
+        authorization: storage::AuthorizationNew,
     ) -> CustomResult<storage::Authorization, errors::StorageError> {
-        // TODO: Implement function for `MockDb`
-        Err(errors::StorageError::MockDbError)?
+        let mut authorizations = self.authorizations.lock().await;
+        if authorizations.iter().any(|authorization_inner| {
+            authorization_inner.authorization_id == authorization.authorization_id
+        }) {
+            Err(errors::StorageError::DuplicateValue {
+                entity: "authorization_id",
+                key: None,
+            })?
+        }
+        let authorization = storage::Authorization {
+            authorization_id: authorization.authorization_id,
+            merchant_id: authorization.merchant_id,
+            payment_id: authorization.payment_id,
+            amount: authorization.amount,
+            created_at: common_utils::date_time::now(),
+            modified_at: common_utils::date_time::now(),
+            status: authorization.status,
+            error_code: authorization.error_code,
+            error_message: authorization.error_message,
+            connector_authorization_id: authorization.connector_authorization_id,
+            previously_authorized_amount: authorization.previously_authorized_amount,
+        };
+        authorizations.push(authorization.clone());
+        Ok(authorization)
     }
 
     async fn find_all_authorizations_by_merchant_id_payment_id(
         &self,
-        _merchant_id: &str,
-        _payment_id: &str,
+        merchant_id: &str,
+        payment_id: &str,
     ) -> CustomResult<Vec<storage::Authorization>, errors::StorageError> {
-        // TODO: Implement function for `MockDb`
-        Err(errors::StorageError::MockDbError)?
+        let authorizations = self.authorizations.lock().await;
+        let authorizations_found: Vec<storage::Authorization> = authorizations
+            .iter()
+            .filter(|a| a.merchant_id == merchant_id && a.payment_id == payment_id)
+            .cloned()
+            .collect();
+
+        Ok(authorizations_found)
     }
 
     async fn update_authorization_by_merchant_id_authorization_id(
         &self,
-        _merchant_id: String,
-        _authorization_id: String,
-        _authorization: storage::AuthorizationUpdate,
+        merchant_id: String,
+        authorization_id: String,
+        authorization_update: storage::AuthorizationUpdate,
     ) -> CustomResult<storage::Authorization, errors::StorageError> {
-        // TODO: Implement function for `MockDb`
-        Err(errors::StorageError::MockDbError)?
+        let mut authorizations = self.authorizations.lock().await;
+        authorizations
+            .iter_mut()
+            .find(|authorization| authorization.authorization_id == authorization_id && authorization.merchant_id == merchant_id)
+            .map(|authorization| {
+                let authorization_updated =
+                    AuthorizationUpdateInternal::from(authorization_update)
+                        .create_authorization(authorization.clone());
+                *authorization = authorization_updated.clone();
+                authorization_updated
+            })
+            .ok_or(
+                errors::StorageError::ValueNotFound(format!(
+                    "cannot find authorization for authorization_id = {authorization_id} and merchant_id = {merchant_id}"
+                ))
+                .into(),
+            )
     }
 }
diff --git a/crates/storage_impl/src/mock_db.rs b/crates/storage_impl/src/mock_db.rs
index e22d39ce70c..a6ba763bd91 100644
--- a/crates/storage_impl/src/mock_db.rs
+++ b/crates/storage_impl/src/mock_db.rs
@@ -43,6 +43,7 @@ pub struct MockDb {
     pub organizations: Arc<Mutex<Vec<store::organization::Organization>>>,
     pub users: Arc<Mutex<Vec<store::user::User>>>,
     pub user_roles: Arc<Mutex<Vec<store::user_role::UserRole>>>,
+    pub authorizations: Arc<Mutex<Vec<store::authorization::Authorization>>>,
     pub dashboard_metadata: Arc<Mutex<Vec<store::user::dashboard_metadata::DashboardMetadata>>>,
 }
 
@@ -79,6 +80,7 @@ impl MockDb {
             organizations: Default::default(),
             users: Default::default(),
             user_roles: Default::default(),
+            authorizations: Default::default(),
             dashboard_metadata: Default::default(),
         })
     }