Use Builder pattern for the services

Cargo.toml

@@ -10,23 +10,39 @@ readme = "./README.md"
 license = "MIT"
 
 [dependencies]
-chrono = {version = "0.4", optional = true, default-features = false, features = ["clock", "serde"] }
-openssl = {version = "0.10", optional = true}
-reqwest = {version = "0.11", features = ["json"]}
-secrecy = "0.8.0"
-serde = {version="1.0", features= ["derive"]}
+chrono = { version = "0.4", optional = true, default-features = false, features = [
+    "clock",
+    "serde",
+] }
+openssl = { version = "0.10", optional = true }
+reqwest = { version = "0.11", features = ["json"] }
+serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 serde_repr = "0.1"
 thiserror = "1.0.37"
 wiremock = "0.5"
+derive_builder = "0.12"
+url = { version = "2", features = ["serde"] }
+secrecy = "0.8"
+
 
 [dev-dependencies]
 dotenv = "0.15"
-tokio = {version = "1", features = ["rt", "rt-multi-thread", "macros"]}
+tokio = { version = "1", features = ["rt", "rt-multi-thread", "macros"] }
 wiremock = "0.5"
 
 [features]
-default = ["account_balance", "b2b", "b2c", "bill_manager", "c2b_register", "c2b_simulate", "express_request", "transaction_reversal", "transaction_status"]
+default = [
+    "account_balance",
+    "b2b",
+    "b2c",
+    "bill_manager",
+    "c2b_register",
+    "c2b_simulate",
+    "express_request",
+    "transaction_reversal",
+    "transaction_status",
+]
 account_balance = ["dep:openssl"]
 b2b = ["dep:openssl"]
 b2c = ["dep:openssl"]
@@ -35,4 +51,4 @@ c2b_register = []
 c2b_simulate = []
 express_request = ["dep:chrono"]
 transaction_reversal = ["dep:openssl"]
-transaction_status= ["dep:openssl"]
+transaction_status = ["dep:openssl"]

src/client.rs

@@ -1,9 +1,9 @@
 use crate::environment::ApiEnvironment;
 use crate::services::{
     AccountBalanceBuilder, B2bBuilder, B2cBuilder, BulkInvoiceBuilder, C2bRegisterBuilder,
-    C2bSimulateBuilder, CancelInvoiceBuilder, MpesaExpressRequestBuilder, OnboardBuilder,
-    OnboardModifyBuilder, ReconciliationBuilder, SingleInvoiceBuilder, TransactionReversalBuilder,
-    TransactionStatusBuilder,
+    C2bSimulateBuilder, CancelInvoiceBuilder, MpesaExpress, MpesaExpressBuilder, OnboardBuilder,
+    OnboardModifyBuilder, ReconciliationBuilder, SingleInvoiceBuilder, TransactionReversal,
+    TransactionReversalBuilder, TransactionStatusBuilder,
 };
 use crate::{ApiError, MpesaError};
 use openssl::base64;
@@ -458,23 +458,17 @@ impl<'mpesa, Env: ApiEnvironment> Mpesa<Env> {
     ///    .send();
     /// ```
     #[cfg(feature = "express_request")]
-    pub fn express_request(
-        &'mpesa self,
-        business_short_code: &'mpesa str,
-    ) -> MpesaExpressRequestBuilder<'mpesa, Env> {
-        MpesaExpressRequestBuilder::new(self, business_short_code)
+    pub fn express_request(&'mpesa self) -> MpesaExpressBuilder<'mpesa, Env> {
+        MpesaExpress::builder(self)
     }
 
     ///**Transaction Reversal Builder**
     /// Reverses a B2B, B2C or C2B M-Pesa transaction.
     ///
     /// See more from the Safaricom API docs [here](https://developer.safaricom.co.ke/Documentation)
     #[cfg(feature = "transaction_reversal")]
-    pub fn transaction_reversal(
-        &'mpesa self,
-        initiator_name: &'mpesa str,
-    ) -> TransactionReversalBuilder<'mpesa, Env> {
-        TransactionReversalBuilder::new(self, initiator_name)
+    pub fn transaction_reversal(&'mpesa self) -> TransactionReversalBuilder<'mpesa, Env> {
+        TransactionReversal::builder(self)
     }
 
     ///**Transaction Status Builder**
@@ -540,7 +534,7 @@ mod tests {
         client.set_initiator_password("foo_bar");
         assert_eq!(client.initiator_password(), "foo_bar".to_string());
     }
-
+    #[derive(Clone)]
     struct TestEnvironment;
 
     impl ApiEnvironment for TestEnvironment {

src/constants.rs

@@ -4,7 +4,7 @@ use serde_repr::{Deserialize_repr, Serialize_repr};
 use std::fmt::{Display, Formatter, Result as FmtResult};
 
 /// Mpesa command ids
-#[derive(Debug, Serialize, Deserialize)]
+#[derive(Debug, Serialize, Clone, Deserialize)]
 pub enum CommandId {
     TransactionReversal,
     SalaryPayment,

src/environment.rs

@@ -26,7 +26,7 @@ pub enum Environment {
 
 /// Expected behavior of an `Mpesa` client environment
 /// This abstraction exists to make it possible to mock the MPESA api server for tests
-pub trait ApiEnvironment {
+pub trait ApiEnvironment: Clone {
     fn base_url(&self) -> &str;
     fn get_certificate(&self) -> &str;
 }

src/errors.rs

@@ -1,8 +1,9 @@
 use serde::{Deserialize, Serialize};
 use std::{env::VarError, fmt};
+use thiserror::Error;
 
 /// Mpesa error stack
-#[derive(thiserror::Error, Debug)]
+#[derive(Error, Debug)]
 pub enum MpesaError {
     #[error("{0}")]
     AuthenticationError(ApiError),
@@ -44,9 +45,11 @@ pub enum MpesaError {
     EncryptionError(#[from] openssl::error::ErrorStack),
     #[error("{0}")]
     Message(&'static str),
+    #[error("An error has occurred while building the request: {0}")]
+    BuilderError(BuilderError),
 }
 
-#[derive(Debug, Serialize, Deserialize)]
+#[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
 pub struct ApiError {
     pub request_id: String,
     pub error_code: String,
@@ -62,3 +65,29 @@ impl fmt::Display for ApiError {
         )
     }
 }
+
+#[derive(Debug, Error)]
+pub enum BuilderError {
+    #[error("Field [{0}] is required")]
+    UninitializedField(&'static str),
+    #[error("Field [{0}] is invalid")]
+    ValidationError(String),
+}
+
+impl From<String> for BuilderError {
+    fn from(s: String) -> Self {
+        Self::ValidationError(s)
+    }
+}
+
+impl From<derive_builder::UninitializedFieldError> for MpesaError {
+    fn from(e: derive_builder::UninitializedFieldError) -> Self {
+        Self::BuilderError(BuilderError::UninitializedField(e.field_name()))
+    }
+}
+
+impl From<url::ParseError> for MpesaError {
+    fn from(e: url::ParseError) -> Self {
+        Self::BuilderError(BuilderError::ValidationError(e.to_string()))
+    }
+}

src/lib.rs

@@ -12,4 +12,4 @@ pub use constants::{
 };
 pub use environment::ApiEnvironment;
 pub use environment::Environment::{self, Production, Sandbox};
-pub use errors::{ApiError, MpesaError};
+pub use errors::{ApiError, BuilderError, MpesaError};