From 7ce80320ed4fb31920f11e7bb3264f231c16918f Mon Sep 17 00:00:00 2001
From: John DiSanti <jdisanti@amazon.com>
Date: Fri, 3 Mar 2023 09:12:45 -0800
Subject: [PATCH] Make it possible to create `SdkError` context structs for
 tests (#2428)

---
 CHANGELOG.next.toml                        |  12 ++
 rust-runtime/aws-smithy-http/src/result.rs | 180 +++++++++++++++++++++
 2 files changed, 192 insertions(+)

diff --git a/CHANGELOG.next.toml b/CHANGELOG.next.toml
index 3b30f2b379..5317cd5c7b 100644
--- a/CHANGELOG.next.toml
+++ b/CHANGELOG.next.toml
@@ -227,3 +227,15 @@ match client.some_operation().send().await {
 references = ["smithy-rs#2398"]
 meta = { "breaking" = false, "tada" = true, "bug" = false }
 author = "ysaito1001"
+
+[[aws-sdk-rust]]
+message = "`SdkError` variants can now be constructed for easier unit testing."
+references = ["smithy-rs#2428", "smithy-rs#2208"]
+meta = { "breaking" = false, "tada" = true, "bug" = false }
+author = "jdisanti"
+
+[[smithy-rs]]
+message = "`SdkError` variants can now be constructed for easier unit testing."
+references = ["smithy-rs#2428", "smithy-rs#2208"]
+meta = { "breaking" = false, "tada" = true, "bug" = false, "target" = "client" }
+author = "jdisanti"
diff --git a/rust-runtime/aws-smithy-http/src/result.rs b/rust-runtime/aws-smithy-http/src/result.rs
index b00667d2c9..f11dcc2d36 100644
--- a/rust-runtime/aws-smithy-http/src/result.rs
+++ b/rust-runtime/aws-smithy-http/src/result.rs
@@ -32,18 +32,183 @@ pub struct SdkSuccess<O> {
     pub parsed: O,
 }
 
+/// Builders for `SdkError` variant context.
+pub mod builders {
+    use super::*;
+
+    macro_rules! source_only_error_builder {
+        ($errorName:ident, $builderName:ident, $sourceType:ident) => {
+            #[doc = concat!("Builder for [`", stringify!($errorName), "`](super::", stringify!($errorName), ").")]
+            #[derive(Debug, Default)]
+            pub struct $builderName {
+                source: Option<$sourceType>,
+            }
+
+            impl $builderName {
+                #[doc = "Creates a new builder."]
+                pub fn new() -> Self { Default::default() }
+
+                #[doc = "Sets the error source."]
+                pub fn source(mut self, source: impl Into<$sourceType>) -> Self {
+                    self.source = Some(source.into());
+                    self
+                }
+
+                #[doc = "Sets the error source."]
+                pub fn set_source(&mut self, source: Option<$sourceType>) -> &mut Self {
+                    self.source = source;
+                    self
+                }
+
+                #[doc = "Builds the error context."]
+                pub fn build(self) -> $errorName {
+                    $errorName { source: self.source.expect("source is required") }
+                }
+            }
+        };
+    }
+
+    source_only_error_builder!(ConstructionFailure, ConstructionFailureBuilder, BoxError);
+    source_only_error_builder!(TimeoutError, TimeoutErrorBuilder, BoxError);
+    source_only_error_builder!(DispatchFailure, DispatchFailureBuilder, ConnectorError);
+
+    /// Builder for [`ResponseError`](super::ResponseError).
+    #[derive(Debug)]
+    pub struct ResponseErrorBuilder<R> {
+        source: Option<BoxError>,
+        raw: Option<R>,
+    }
+
+    impl<R> Default for ResponseErrorBuilder<R> {
+        fn default() -> Self {
+            Self {
+                source: None,
+                raw: None,
+            }
+        }
+    }
+
+    impl<R> ResponseErrorBuilder<R> {
+        /// Creates a new builder.
+        pub fn new() -> Self {
+            Default::default()
+        }
+
+        /// Sets the error source.
+        pub fn source(mut self, source: impl Into<BoxError>) -> Self {
+            self.source = Some(source.into());
+            self
+        }
+
+        /// Sets the error source.
+        pub fn set_source(&mut self, source: Option<BoxError>) -> &mut Self {
+            self.source = source;
+            self
+        }
+
+        /// Sets the raw response.
+        pub fn raw(mut self, raw: R) -> Self {
+            self.raw = Some(raw);
+            self
+        }
+
+        /// Sets the raw response.
+        pub fn set_raw(&mut self, raw: Option<R>) -> &mut Self {
+            self.raw = raw;
+            self
+        }
+
+        /// Builds the error context.
+        pub fn build(self) -> ResponseError<R> {
+            ResponseError {
+                source: self.source.expect("source is required"),
+                raw: self.raw.expect("a raw response is required"),
+            }
+        }
+    }
+
+    /// Builder for [`ServiceError`](super::ServiceError).
+    #[derive(Debug)]
+    pub struct ServiceErrorBuilder<E, R> {
+        source: Option<E>,
+        raw: Option<R>,
+    }
+
+    impl<E, R> Default for ServiceErrorBuilder<E, R> {
+        fn default() -> Self {
+            Self {
+                source: None,
+                raw: None,
+            }
+        }
+    }
+
+    impl<E, R> ServiceErrorBuilder<E, R> {
+        /// Creates a new builder.
+        pub fn new() -> Self {
+            Default::default()
+        }
+
+        /// Sets the error source.
+        pub fn source(mut self, source: impl Into<E>) -> Self {
+            self.source = Some(source.into());
+            self
+        }
+
+        /// Sets the error source.
+        pub fn set_source(&mut self, source: Option<E>) -> &mut Self {
+            self.source = source;
+            self
+        }
+
+        /// Sets the raw response.
+        pub fn raw(mut self, raw: R) -> Self {
+            self.raw = Some(raw);
+            self
+        }
+
+        /// Sets the raw response.
+        pub fn set_raw(&mut self, raw: Option<R>) -> &mut Self {
+            self.raw = raw;
+            self
+        }
+
+        /// Builds the error context.
+        pub fn build(self) -> ServiceError<E, R> {
+            ServiceError {
+                source: self.source.expect("source is required"),
+                raw: self.raw.expect("a raw response is required"),
+            }
+        }
+    }
+}
+
 /// Error context for [`SdkError::ConstructionFailure`]
 #[derive(Debug)]
 pub struct ConstructionFailure {
     source: BoxError,
 }
 
+impl ConstructionFailure {
+    /// Creates a builder for this error context type.
+    pub fn builder() -> builders::ConstructionFailureBuilder {
+        builders::ConstructionFailureBuilder::new()
+    }
+}
+
 /// Error context for [`SdkError::TimeoutError`]
 #[derive(Debug)]
 pub struct TimeoutError {
     source: BoxError,
 }
 
+impl TimeoutError {
+    /// Creates a builder for this error context type.
+    pub fn builder() -> builders::TimeoutErrorBuilder {
+        builders::TimeoutErrorBuilder::new()
+    }
+}
+
 /// Error context for [`SdkError::DispatchFailure`]
 #[derive(Debug)]
 pub struct DispatchFailure {
@@ -51,6 +216,11 @@ pub struct DispatchFailure {
 }
 
 impl DispatchFailure {
+    /// Creates a builder for this error context type.
+    pub fn builder() -> builders::DispatchFailureBuilder {
+        builders::DispatchFailureBuilder::new()
+    }
+
     /// Returns true if the error is an IO error
     pub fn is_io(&self) -> bool {
         self.source.is_io()
@@ -82,6 +252,11 @@ pub struct ResponseError<R> {
 }
 
 impl<R> ResponseError<R> {
+    /// Creates a builder for this error context type.
+    pub fn builder() -> builders::ResponseErrorBuilder<R> {
+        builders::ResponseErrorBuilder::new()
+    }
+
     /// Returns a reference to the raw response
     pub fn raw(&self) -> &R {
         &self.raw
@@ -103,6 +278,11 @@ pub struct ServiceError<E, R> {
 }
 
 impl<E, R> ServiceError<E, R> {
+    /// Creates a builder for this error context type.
+    pub fn builder() -> builders::ServiceErrorBuilder<E, R> {
+        builders::ServiceErrorBuilder::new()
+    }
+
     /// Returns the underlying error of type `E`
     pub fn err(&self) -> &E {
         &self.source