From 3f8e287c68d3b11ba15309982846f09dbab23067 Mon Sep 17 00:00:00 2001
From: andrussal <salumets.andrus@gmail.com>
Date: Sun, 8 Mar 2026 13:44:25 +0100
Subject: [PATCH] Make scenario source transitions explicit

---
 .../core/src/scenario/definition.rs           |  6 +++---
 .../core/src/scenario/sources/model.rs        | 19 +++++++++++++------
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/testing-framework/core/src/scenario/definition.rs b/testing-framework/core/src/scenario/definition.rs
index 44b210c..f656a98 100644
--- a/testing-framework/core/src/scenario/definition.rs
+++ b/testing-framework/core/src/scenario/definition.rs
@@ -569,13 +569,13 @@ impl<E: Application, Caps> Builder<E, Caps> {
 
     #[must_use]
     pub fn with_attach_source(mut self, attach: AttachSource) -> Self {
-        self.sources.set_attach(attach);
+        self.sources = self.sources.with_attach(attach);
         self
     }
 
     #[must_use]
     pub fn with_external_node(mut self, node: ExternalNodeSource) -> Self {
-        self.sources.add_external_node(node);
+        self.sources = self.sources.with_external_node(node);
         self
     }
 
@@ -591,7 +591,7 @@ impl<E: Application, Caps> Builder<E, Caps> {
 
     #[must_use]
     pub fn with_external_only_sources(mut self) -> Self {
-        self.sources.set_external_only();
+        self.sources = self.sources.into_external_only();
         self
     }
 
diff --git a/testing-framework/core/src/scenario/sources/model.rs b/testing-framework/core/src/scenario/sources/model.rs
index c107d7c..84dc89f 100644
--- a/testing-framework/core/src/scenario/sources/model.rs
+++ b/testing-framework/core/src/scenario/sources/model.rs
@@ -128,22 +128,29 @@ impl ScenarioSources {
         Self::ExternalOnly { external }
     }
 
-    pub(crate) fn add_external_node(&mut self, node: ExternalNodeSource) {
-        match self {
+    #[must_use]
+    pub fn with_external_node(mut self, node: ExternalNodeSource) -> Self {
+        match &mut self {
             Self::Managed { external }
             | Self::Attached { external, .. }
             | Self::ExternalOnly { external } => external.push(node),
         }
+
+        self
     }
 
-    pub(crate) fn set_attach(&mut self, attach: AttachSource) {
+    #[must_use]
+    pub fn with_attach(self, attach: AttachSource) -> Self {
         let external = self.external_nodes().to_vec();
-        *self = Self::Attached { attach, external };
+
+        Self::Attached { attach, external }
     }
 
-    pub(crate) fn set_external_only(&mut self) {
+    #[must_use]
+    pub fn into_external_only(self) -> Self {
         let external = self.external_nodes().to_vec();
-        *self = Self::ExternalOnly { external };
+
+        Self::ExternalOnly { external }
     }
 
     #[must_use]