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



Spin out from https://github.com/juspay/hyperswitch/issues/172. Please refer to that issue for more information.

Pull request description:
## Type of Change
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- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
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### 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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1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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that will have little conversation).
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Closes #1116.

## How did you test it?
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## Checklist
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- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed 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/router/src/db.rs b/crates/router/src/db.rs
index ee9cd03e692..a260f016dc8 100644
--- a/crates/router/src/db.rs
+++ b/crates/router/src/db.rs
@@ -85,6 +85,7 @@ pub struct MockDb {
     redis: Arc<redis_interface::RedisConnectionPool>,
     api_keys: Arc<Mutex<Vec<storage::ApiKey>>>,
     cards_info: Arc<Mutex<Vec<storage::CardInfo>>>,
+    events: Arc<Mutex<Vec<storage::Event>>>,
 }
 
 impl MockDb {
@@ -102,6 +103,7 @@ impl MockDb {
             redis: Arc::new(crate::connection::redis_connection(redis).await),
             api_keys: Default::default(),
             cards_info: Default::default(),
+            events: Default::default(),
         }
     }
 }
diff --git a/crates/router/src/db/events.rs b/crates/router/src/db/events.rs
index aed2f285bfb..8148f2a8a8b 100644
--- a/crates/router/src/db/events.rs
+++ b/crates/router/src/db/events.rs
@@ -46,16 +46,94 @@ impl EventInterface for Store {
 impl EventInterface for MockDb {
     async fn insert_event(
         &self,
-        _event: storage::EventNew,
+        event: storage::EventNew,
     ) -> CustomResult<storage::Event, errors::StorageError> {
-        // [#172]: Implement function for `MockDb`
-        Err(errors::StorageError::MockDbError)?
+        let mut locked_events = self.events.lock().await;
+        let now = common_utils::date_time::now();
+
+        let stored_event = storage::Event {
+            #[allow(clippy::as_conversions)]
+            id: locked_events.len() as i32,
+            event_id: event.event_id,
+            event_type: event.event_type,
+            event_class: event.event_class,
+            is_webhook_notified: event.is_webhook_notified,
+            intent_reference_id: event.intent_reference_id,
+            primary_object_id: event.primary_object_id,
+            primary_object_type: event.primary_object_type,
+            created_at: now,
+        };
+
+        locked_events.push(stored_event.clone());
+
+        Ok(stored_event)
     }
     async fn update_event(
         &self,
-        _event_id: String,
-        _event: storage::EventUpdate,
+        event_id: String,
+        event: storage::EventUpdate,
     ) -> CustomResult<storage::Event, errors::StorageError> {
-        Err(errors::StorageError::MockDbError)?
+        let mut locked_events = self.events.lock().await;
+        let mut event_to_update = locked_events
+            .iter_mut()
+            .find(|e| e.event_id == event_id)
+            .ok_or(errors::StorageError::MockDbError)?;
+
+        match event {
+            storage::EventUpdate::UpdateWebhookNotified {
+                is_webhook_notified,
+            } => {
+                if let Some(is_webhook_notified) = is_webhook_notified {
+                    event_to_update.is_webhook_notified = is_webhook_notified;
+                }
+            }
+        }
+
+        Ok(event_to_update.clone())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use storage_models::enums;
+
+    use crate::{
+        db::{events::EventInterface, MockDb},
+        types::storage,
+    };
+
+    #[allow(clippy::unwrap_used)]
+    #[tokio::test]
+    async fn test_mockdb_event_interface() {
+        let mockdb = MockDb::new(&Default::default()).await;
+
+        let event1 = mockdb
+            .insert_event(storage::EventNew {
+                event_id: "test_event_id".into(),
+                event_type: enums::EventType::PaymentSucceeded,
+                event_class: enums::EventClass::Payments,
+                is_webhook_notified: false,
+                intent_reference_id: Some("test".into()),
+                primary_object_id: "primary_object_tet".into(),
+                primary_object_type: enums::EventObjectType::PaymentDetails,
+            })
+            .await
+            .unwrap();
+
+        assert_eq!(event1.id, 0);
+
+        let updated_event = mockdb
+            .update_event(
+                "test_event_id".into(),
+                storage::EventUpdate::UpdateWebhookNotified {
+                    is_webhook_notified: Some(true),
+                },
+            )
+            .await
+            .unwrap();
+
+        assert!(updated_event.is_webhook_notified);
+        assert_eq!(updated_event.primary_object_id, "primary_object_tet");
+        assert_eq!(updated_event.id, 0);
     }
 }