refactor: fix unit and documentation tests (#4754)

.github/nextest.toml

@@ -0,0 +1,11 @@
+[profile.default]
+status-level = "slow"
+final-status-level = "leak"
+failure-output = "final"
+fail-fast = false
+
+[profile.ci]
+retries = 2
+status-level = "all"
+failure-output = "final"
+fail-fast = false

.github/workflows/CI-pr.yml

@@ -33,8 +33,8 @@ env:
   RUSTUP_MAX_RETRIES: 10
   # Don't emit giant backtraces in the CI logs.
   RUST_BACKTRACE: short
-  # Use cargo's sparse index protocol
+  # Use `sccache` for caching compilation artifacts
-  CARGO_REGISTRIES_CRATES_IO_PROTOCOL: sparse
+  RUSTC_WRAPPER: sccache
 
 jobs:
   formatting:
@@ -88,14 +88,7 @@ jobs:
 
   check-msrv:
     name: Check compilation on MSRV toolchain
-    runs-on: ${{ matrix.os }}
+    runs-on: hyperswitch-runners
-    strategy:
-      fail-fast: true
-      matrix:
-        os:
-          - ubuntu-latest
-        # - macos-latest
-        # - windows-latest
 
     steps:
       - name: Checkout repository
@@ -122,14 +115,17 @@ jobs:
         with:
           toolchain: "${{ env.rust_version }}"
 
-      - uses: Swatinem/rust-cache@v2.7.0
+      - name: Install sccache
+        uses: taiki-e/install-action@v2.33.28
         with:
-          save-if: false
+          tool: sccache
+          checksum: true
 
       - name: Install cargo-hack
-        uses: baptiste0928/cargo-install@v2.2.0
+        uses: taiki-e/install-action@v2.33.28
         with:
-          crate: cargo-hack
+          tool: cargo-hack
+          checksum: true
 
       - name: Deny warnings
         shell: bash
@@ -210,14 +206,7 @@ jobs:
 
   test:
     name: Run tests on stable toolchain
-    runs-on: ${{ matrix.os }}
+    runs-on: hyperswitch-runners
-    strategy:
-      fail-fast: false
-      matrix:
-        os:
-          - ubuntu-latest
-        # - macos-latest
-        # - windows-latest
 
     steps:
       - name: Generate a token
@@ -256,19 +245,23 @@ jobs:
           toolchain: stable 2 weeks ago
           components: clippy
 
-      - name: Install cargo-hack
+      - name: Install sccache
-        uses: baptiste0928/cargo-install@v2.2.0
+        uses: taiki-e/install-action@v2.33.28
         with:
-          crate: cargo-hack
+          tool: sccache
+          checksum: true
+
+      - name: Install cargo-hack
+        uses: taiki-e/install-action@v2.33.28
+        with:
+          tool: cargo-hack
+          checksum: true
 
       # - name: Install cargo-nextest
-      #   uses: baptiste0928/cargo-install@v2.2.0
+      #   uses: taiki-e/install-action@v2.33.28
       #   with:
-      #     crate: cargo-nextest
+      #     tool: cargo-nextest
-
+      #     checksum: true
-      - uses: Swatinem/rust-cache@v2.7.0
-        with:
-          save-if: false
 
       # - name: Setup Embark Studios lint rules
       #   shell: bash

.github/workflows/CI-push.yml

@@ -39,14 +39,7 @@ jobs:
 
   check-msrv:
     name: Check compilation on MSRV toolchain
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: true
-      matrix:
-        os:
-          - ubuntu-latest
-        # - macos-latest
-        # - windows-latest
 
     steps:
       - name: Checkout repository
@@ -115,14 +108,7 @@ jobs:
 
   test:
     name: Run tests on stable toolchain
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        os:
-          - ubuntu-latest
-        # - macos-latest
-        # - windows-latest
 
     steps:
       - name: Checkout repository

Cargo.lock

@@ -6030,7 +6030,9 @@ dependencies = [
 name = "router_derive"
 version = "0.1.0"
 dependencies = [
+ "common_utils",
  "diesel",
+ "error-stack",
  "indexmap 2.2.6",
  "proc-macro2",
  "quote",
@@ -6038,6 +6040,7 @@ dependencies = [
  "serde_json",
  "strum 0.26.2",
  "syn 2.0.57",
+ "utoipa",
 ]
 
 [[package]]

crates/euclid/src/dssa/analyzer.rs

@@ -314,6 +314,7 @@ mod tests {
                                     & payment_method /= voucher
                                     & payment_method /= gift_card
                                     & payment_method /= card_redirect
+                                    & payment_method /= real_time_payment
                             }
                         }
                     }

crates/external_services/src/hashicorp_vault/core.rs

@@ -163,7 +163,8 @@ pub trait FromEncoded: Sized {
     /// # Example
     ///
     /// ```rust
-    /// # use your_module::{FromEncoded, masking::Secret, Vec};
+    /// use external_services::hashicorp_vault::core::FromEncoded;
+    /// use masking::Secret;
     /// let secret_instance = Secret::<String>::from_encoded("encoded_secret_string".to_string());
     /// let vec_instance = Vec::<u8>::from_encoded("68656c6c6f".to_string());
     /// ```

crates/hyperswitch_domain_models/src/router_request_types.rs

@@ -22,7 +22,7 @@ pub struct PaymentsAuthorizeData {
     pub payment_method_data: PaymentMethodData,
     /// total amount (original_amount + surcharge_amount + tax_on_surcharge_amount)
     /// If connector supports separate field for surcharge amount, consider using below functions defined on `PaymentsAuthorizeData` to fetch original amount and surcharge amount separately
-    /// ```
+    /// ```text
     /// get_original_amount()
     /// get_surcharge_amount()
     /// get_tax_on_surcharge_amount()

crates/masking/README.md

@@ -15,26 +15,43 @@ This solution has such advantages over alternatives:
 
 ## How to use
 
-To convert non-secret variable into secret use `new()`. Sample:
+To convert a non-secret variable into a secret, use `Secret::new()`:
 
 ```rust
-expiry_year: ccard.map(|x| Secret::new(x.card_exp_year.to_string())),
+use masking::Secret;
-// output: "expiry_year: *** alloc::string::String ***"
+
+let card_number: Secret<String> = Secret::new(String::from("1234 5678 9012 3456"));
+assert_eq!(format!("{:?}", card_number), "*** alloc::string::String ***");
 ```
 
-To get value from secret use `expose()`. Sample:
+To get a reference to the inner value from the secret, use `peek()`:
 
 ```rust
-last4_digits: Some(card_number.expose())
+use masking::{PeekInterface, Secret};
+
+let card_number: Secret<String> = Secret::new(String::from("1234 5678 9012 3456"));
+let last4_digits: &str = card_number.peek();
 ```
 
-Most fields are under `Option`. To simplify dealing with `Option`, use `expose_option()`. Sample:
+To get the owned inner value from the secret, use `expose()`:
 
 ```rust
-    card_info.push_str(
+use masking::{ExposeInterface, Secret};
-        &card_detail
+
-            .card_holder_name
+let card_number: Secret<String> = Secret::new(String::from("1234 5678 9012 3456"));
-            .expose_option()
+let last4_digits: String = card_number.expose();
-            .unwrap_or_default(),
+```
-    );
+
+For fields that are `Option<T>`, you can use `expose_option()`:
+
+```rust
+use masking::{ExposeOptionInterface, Secret};
+
+let card_number: Option<Secret<String>> = Some(Secret::new(String::from("1234 5678 9012 3456")));
+let card_number_str: String = card_number.expose_option().unwrap_or_default();
+assert_eq!(format!("{}", card_number_str), "1234 5678 9012 3456");
+
+let card_number: Option<Secret<String>> = None;
+let card_number_str: String = card_number.expose_option().unwrap_or_default();
+assert_eq!(format!("{}", card_number_str), "");
 ```

crates/router/src/configs/settings.rs

@@ -1001,15 +1001,10 @@ mod hashmap_deserialization_test {
     fn test_payment_method_and_payment_method_types() {
         use diesel_models::enums::{PaymentMethod, PaymentMethodType};
 
-        let input_map: HashMap<String, String> = serde_json::json!({
+        let input_map: HashMap<String, String> = HashMap::from([
-            "bank_transfer": "ach,bacs",
+            ("bank_transfer".to_string(), "ach,bacs".to_string()),
-            "wallet": "paypal,venmo",
+            ("wallet".to_string(), "paypal,venmo".to_string()),
-        })
+        ]);
-        .as_object()
-        .unwrap()
-        .iter()
-        .map(|(k, v)| (k.to_string(), v.to_string()))
-        .collect();
         let deserializer: MapDeserializer<
             '_,
             std::collections::hash_map::IntoIter<String, String>,
@@ -1035,15 +1030,10 @@ mod hashmap_deserialization_test {
     fn test_payment_method_and_payment_method_types_with_spaces() {
         use diesel_models::enums::{PaymentMethod, PaymentMethodType};
 
-        let input_map: HashMap<String, String> = serde_json::json!({
+        let input_map: HashMap<String, String> = HashMap::from([
-            " bank_transfer ": " ach , bacs ",
+            (" bank_transfer ".to_string(), " ach , bacs ".to_string()),
-            "wallet ": " paypal , pix , venmo ",
+            ("wallet ".to_string(), " paypal , pix , venmo ".to_string()),
-        })
+        ]);
-        .as_object()
-        .unwrap()
-        .iter()
-        .map(|(k, v)| (k.to_string(), v.to_string()))
-        .collect();
         let deserializer: MapDeserializer<
             '_,
             std::collections::hash_map::IntoIter<String, String>,
@@ -1073,15 +1063,10 @@ mod hashmap_deserialization_test {
     fn test_payment_method_deserializer_error() {
         use diesel_models::enums::{PaymentMethod, PaymentMethodType};
 
-        let input_map: HashMap<String, String> = serde_json::json!({
+        let input_map: HashMap<String, String> = HashMap::from([
-            "unknown": "ach,bacs",
+            ("unknown".to_string(), "ach,bacs".to_string()),
-            "wallet": "paypal,unknown",
+            ("wallet".to_string(), "paypal,unknown".to_string()),
-        })
+        ]);
-        .as_object()
-        .unwrap()
-        .iter()
-        .map(|(k, v)| (k.to_string(), v.to_string()))
-        .collect();
         let deserializer: MapDeserializer<
             '_,
             std::collections::hash_map::IntoIter<String, String>,

crates/router/src/connector/netcetera/netcetera_types.rs

@@ -118,8 +118,8 @@ pub struct ThreeDSRequestor {
     /// External IP address (i.e., the device public IP address) used by the 3DS Requestor App when it connects to the
     /// 3DS Requestor environment. The value length is maximum 45 characters. Accepted values are:
     ///
-    ///     IPv4 address is represented in the dotted decimal f. Refer to RFC 791.
+    /// - IPv4 address is represented in the dotted decimal f. Refer to RFC 791.
-    ///     IPv6 address. Refer to RFC 4291.
+    /// - IPv6 address. Refer to RFC 4291.
     ///
     /// This field is required when deviceChannel = 01 (APP) and unless market or regional mandate restricts sending
     /// this information.
@@ -1454,17 +1454,17 @@ pub struct Sdk {
     /// The Split-SDK Server:
     ///    Creates a JSON object of the following data as the JWS payload to be signed:
     ///
-    ///        SDK Reference Number -> Identifies the vendor and version of the 3DS SDK that is utilised for a specific
+    ///    - SDK Reference Number -> Identifies the vendor and version of the 3DS SDK that is utilised for a specific
     ///                              transaction. The value is assigned by EMVCo when the Letter of Approval of the
     ///                              specific 3DS SDK is issued. The field is limited to 32 characters.
-    ///        SDK Signature Timestamp -> Date and time indicating when the 3DS SDK generated the Split-SDK Server Signed
+    ///    - SDK Signature Timestamp -> Date and time indicating when the 3DS SDK generated the Split-SDK Server Signed
     ///                                 Content converted into UTC. The value is limited to 14 characters. Accepted
     ///                                 format: YYYYMMDDHHMMSS.
-    ///        SDK Transaction ID -> Universally unique transaction identifier assigned by the 3DS SDK to identify a
+    ///    - SDK Transaction ID -> Universally unique transaction identifier assigned by the 3DS SDK to identify a
     ///                            single transaction. The field is limited to 36 characters and it shall be in a
     ///                            canonical format as defined in IETF RFC 4122. This may utilize any of the specified
     ///                            versions as long as the output meets specific requirements.
-    ///        Split-SDK Server ID -> DS assigned Split-SDK Server identifier. Each DS can provide a unique ID to each
+    ///    - Split-SDK Server ID -> DS assigned Split-SDK Server identifier. Each DS can provide a unique ID to each
     ///                             Split-SDK Server on an individual basis. The field is limited to 32 characters.
     ///                             Any individual DS may impose specific formatting and character requirements on the
     ///                             contents of this field.
@@ -1473,8 +1473,8 @@ pub struct Sdk {
     ///    Serialization. The parameter values for this version of the specification and to be included in the JWS
     ///    header are:
     ///
-    ///        "alg": PS2567 or ES256
+    ///    - `alg`: PS2567 or ES256
-    ///        "x5c": X.5C v3: Cert (PbSDK) and chaining certificates if present
+    ///    - `x5c`: X.5C v3: Cert (PbSDK) and chaining certificates if present
     ///
     ///    All other parameters: optional
     ///

crates/router/src/core/payments/helpers.rs

@@ -3098,7 +3098,7 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test_authenticate_client_secret_fulfillment_time_not_expired() {
+    fn test_authenticate_client_secret_session_not_expired() {
         let payment_intent = PaymentIntent {
             payment_id: "23".to_string(),
             merchant_id: "22".to_string(),
@@ -3160,7 +3160,9 @@ mod tests {
     }
 
     #[test]
-    fn test_authenticate_client_secret_fulfillment_time_expired() {
+    fn test_authenticate_client_secret_session_expired() {
+        let created_at =
+            common_utils::date_time::now().saturating_sub(time::Duration::seconds(20 * 60));
         let payment_intent = PaymentIntent {
             payment_id: "23".to_string(),
             merchant_id: "22".to_string(),
@@ -3177,7 +3179,7 @@ mod tests {
             billing_address_id: None,
             statement_descriptor_name: None,
             statement_descriptor_suffix: None,
-            created_at: common_utils::date_time::now().saturating_sub(time::Duration::seconds(20)),
+            created_at,
             modified_at: common_utils::date_time::now(),
             fingerprint_id: None,
             last_synced: None,
@@ -3206,8 +3208,7 @@ mod tests {
             incremental_authorization_allowed: None,
             authorization_count: None,
             session_expiry: Some(
-                common_utils::date_time::now()
+                created_at.saturating_add(time::Duration::seconds(consts::DEFAULT_SESSION_EXPIRY)),
-                    .saturating_add(time::Duration::seconds(consts::DEFAULT_SESSION_EXPIRY)),
             ),
             request_external_three_ds_authentication: None,
             charges: None,

crates/router/src/db/events.rs

@@ -754,7 +754,7 @@ mod tests {
             .unwrap();
 
         assert!(updated_event.is_webhook_notified);
-        assert_eq!(updated_event.primary_object_id, "primary_object_tet");
+        assert_eq!(updated_event.primary_object_id, payment_id);
         assert_eq!(updated_event.event_id, event_id);
     }
 }

crates/router/src/types/storage/payment_attempt.rs

@@ -99,20 +99,28 @@ mod tests {
         types::{self, storage::enums},
     };
 
-    #[actix_rt::test]
+    async fn create_single_connection_test_transaction_pool() -> routes::AppState {
-    #[ignore]
+        // Set pool size to 1 and minimum idle connection size to 0
-    async fn test_payment_attempt_insert() {
+        std::env::set_var("ROUTER__MASTER_DATABASE__POOL_SIZE", "1");
+        std::env::set_var("ROUTER__MASTER_DATABASE__MIN_IDLE", "0");
+        std::env::set_var("ROUTER__REPLICA_DATABASE__POOL_SIZE", "1");
+        std::env::set_var("ROUTER__REPLICA_DATABASE__MIN_IDLE", "0");
+
         let conf = Settings::new().expect("invalid settings");
         let tx: oneshot::Sender<()> = oneshot::channel().0;
         let api_client = Box::new(services::MockApiClient);
-        let state = Box::pin(routes::AppState::with_storage(
+        Box::pin(routes::AppState::with_storage(
             conf,
             StorageImpl::PostgresqlTest,
             tx,
             api_client,
         ))
-        .await;
+        .await
+    }
 
+    #[tokio::test]
+    async fn test_payment_attempt_insert() {
+        let state = create_single_connection_test_transaction_pool().await;
         let payment_id = Uuid::new_v4().to_string();
         let current_time = common_utils::date_time::now();
         let connector = types::Connector::DummyConnector1.to_string();
@@ -137,22 +145,11 @@ mod tests {
         assert_eq!(response.payment_id, payment_id.clone());
     }
 
-    #[actix_rt::test]
+    #[tokio::test]
     /// Example of unit test
     /// Kind of test: state-based testing
     async fn test_find_payment_attempt() {
-        use crate::configs::settings::Settings;
+        let state = create_single_connection_test_transaction_pool().await;
-        let conf = Settings::new().expect("invalid settings");
-        let tx: oneshot::Sender<()> = oneshot::channel().0;
-        let api_client = Box::new(services::MockApiClient);
-        let state = Box::pin(routes::AppState::with_storage(
-            conf,
-            StorageImpl::PostgresqlTest,
-            tx,
-            api_client,
-        ))
-        .await;
-
         let current_time = common_utils::date_time::now();
         let payment_id = Uuid::new_v4().to_string();
         let attempt_id = Uuid::new_v4().to_string();
@@ -192,23 +189,12 @@ mod tests {
         assert_eq!(response.payment_id, payment_id);
     }
 
-    #[actix_rt::test]
+    #[tokio::test]
     /// Example of unit test
     /// Kind of test: state-based testing
     async fn test_payment_attempt_mandate_field() {
-        use crate::configs::settings::Settings;
+        let state = create_single_connection_test_transaction_pool().await;
-        let conf = Settings::new().expect("invalid settings");
         let uuid = Uuid::new_v4().to_string();
-        let tx: oneshot::Sender<()> = oneshot::channel().0;
-
-        let api_client = Box::new(services::MockApiClient);
-        let state = Box::pin(routes::AppState::with_storage(
-            conf,
-            StorageImpl::PostgresqlTest,
-            tx,
-            api_client,
-        ))
-        .await;
         let current_time = common_utils::date_time::now();
         let connector = types::Connector::DummyConnector1.to_string();
 

crates/router_derive/Cargo.toml

@@ -20,5 +20,9 @@ strum = { version = "0.26.2", features = ["derive"] }
 
 [dev-dependencies]
 diesel = { version = "2.1.5", features = ["postgres"] }
+error-stack = "0.4.1"
 serde = { version = "1.0.197", features = ["derive"] }
 serde_json = "1.0.115"
+utoipa = "4.2.0"
+
+common_utils = { version = "0.1.0", path = "../common_utils" }

crates/router_derive/src/lib.rs

@@ -63,7 +63,7 @@ pub fn debug_as_display_derive(input: proc_macro::TokenStream) -> proc_macro::To
 /// // yourself if required.
 /// #[derive(strum::Display, strum::EnumString)]
 /// #[derive(Debug)]
-/// #[diesel_enum(storage_type = "pg_enum")]
+/// #[diesel_enum(storage_type = "db_enum")]
 /// enum Color {
 ///     Red,
 ///     Green,
@@ -153,12 +153,14 @@ pub fn diesel_enum(
 /// # Example
 /// ```
 /// use router_derive::Setter;
+///
+/// #[derive(Setter)]
 /// struct Test {
 ///     test:u32
 /// }
 /// ```
 /// The above Example will expand to
-/// ```
+/// ```rust, ignore
 /// impl Test {
 ///     fn set_test(&mut self, val: u32) -> &mut Self {
 ///         self.test = val;
@@ -381,7 +383,7 @@ pub fn api_error_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStre
 /// - update_tracker
 ///
 /// ## Example
-/// ```
+/// ```rust, ignore
 /// use router_derive::Operation;
 ///
 /// #[derive(Operation)]
@@ -470,12 +472,14 @@ pub fn operation_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStre
 /// Generates different schemas with the ability to mark few fields as mandatory for certain schema
 /// Usage
 /// ```
+/// use router_derive::PolymorphicSchema;
+///
 /// #[derive(PolymorphicSchema)]
 /// #[generate_schemas(PaymentsCreateRequest, PaymentsConfirmRequest)]
 /// struct PaymentsRequest {
-///     #[mandatory_in(PaymentsCreateRequest)]
+///     #[mandatory_in(PaymentsCreateRequest = u64)]
 ///     amount: Option<u64>,
-///     #[mandatory_in(PaymentsCreateRequest)]
+///     #[mandatory_in(PaymentsCreateRequest = String)]
 ///     currency: Option<String>,
 ///     payment_method: String,
 /// }
@@ -520,6 +524,17 @@ pub fn polymorphic_schema(input: proc_macro::TokenStream) -> proc_macro::TokenSt
 /// Implements the `Validate` trait to check if the config variable is present
 /// Usage
 /// ```
+/// use router_derive::ConfigValidate;
+///
+/// #[derive(ConfigValidate)]
+/// struct ConnectorParams {
+///     base_url: String,
+/// }
+///
+/// enum ApplicationError {
+///     InvalidConfigurationValueError(String),
+/// }
+///
 /// #[derive(ConfigValidate)]
 /// struct Connectors {
 ///     pub stripe: ConnectorParams,
@@ -529,7 +544,7 @@ pub fn polymorphic_schema(input: proc_macro::TokenStream) -> proc_macro::TokenSt
 ///
 /// This will call the `validate()` function for all the fields in the struct
 ///
-/// ```
+/// ```rust, ignore
 /// impl Connectors {
 ///      fn validate(&self) -> Result<(), ApplicationError> {
 ///         self.stripe.validate()?;
@@ -549,9 +564,26 @@ pub fn validate_config(input: proc_macro::TokenStream) -> proc_macro::TokenStrea
 /// Generates the function to get the value out of enum variant
 /// Usage
 /// ```
+/// use router_derive::TryGetEnumVariant;
+///
+/// impl std::fmt::Display for RedisError {
+///     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+///         match self {
+///             Self::UnknownResult => write!(f, "Unknown result")
+///         }
+///     }
+/// }
+///
+/// impl std::error::Error for RedisError {}
+///
+/// #[derive(Debug)]
+/// enum RedisError {
+///     UnknownResult
+/// }
+///
 /// #[derive(TryGetEnumVariant)]
-/// #[error(RedisError(UnknownResult))]
+/// #[error(RedisError::UnknownResult)]
-/// enum Result {
+/// enum RedisResult {
 ///     Set(String),
 ///     Get(i32)
 /// }
@@ -559,8 +591,8 @@ pub fn validate_config(input: proc_macro::TokenStream) -> proc_macro::TokenStrea
 ///
 /// This will generate the function to get `String` and `i32` out of the variants
 ///
-/// ```
+/// ```rust, ignore
-/// impl Result {
+/// impl RedisResult {
 ///     fn try_into_get(&self)-> Result<i32, RedisError> {
 ///         match self {
 ///             Self::Get(a) => Ok(a),
@@ -575,6 +607,7 @@ pub fn validate_config(input: proc_macro::TokenStream) -> proc_macro::TokenStrea
 ///         }
 ///     }
 /// }
+/// ```
 #[proc_macro_derive(TryGetEnumVariant, attributes(error))]
 pub fn try_get_enum_variant(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let input = syn::parse_macro_input!(input as syn::DeriveInput);

crates/router_env/README.md

@@ -5,6 +5,9 @@ Environment of payment router: logger, basic config, its environment awareness.
 ## Example
 
 ```rust
+use router_env::logger;
+use tracing::{self, instrument};
+
 #[instrument]
 pub fn sample() -> () {
     logger::log!(

crates/router_env/src/logger/formatter.rs

@@ -152,7 +152,7 @@ where
     ///
     /// ## Example
     /// ```rust
-    /// let formatting_layer = router_env::FormattingLayer::new(router_env::service_name!(),std::io::stdout, CompactFormatter);
+    /// let formatting_layer = router_env::FormattingLayer::new("my_service", std::io::stdout, serde_json::ser::CompactFormatter);
     /// ```
     ///
     pub fn new(service: &str, dst_writer: W, formatter: F) -> Self {