input-output-hk · Alenar · Jul 22, 2025 · Jul 17, 2025 · Jul 17, 2025 · Jul 21, 2025
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/DEV-ADR.md b/DEV-ADR.md
@@ -23,6 +23,34 @@ To complete
 To complete
 -->
 
+### 3. Guidelines for Dummy Test Doubles
+
+**Date:** 2025-07-22
+**Status:** Accepted
+
+#### Context
+
+The use of `dummy()` functions for creating test doubles is widespread across the codebase. However, inconsistencies
+in their placement and visibility have led to maintenance challenges and reduced code clarity.
+
+#### Decision
+
+A `Dummy` trait will be introduced, functioning similarly to Rust's `Default` trait.
+
+The following guidelines will be adopted for implementing the `Dummy` trait:
+
+1. Most implementations should reside in a `test::double::dummies` module within the crate where the type is defined.
+2. For types with non-public fields, the `Dummy` trait should be implemented directly below the type's definition.
+
+#### Consequences
+
+- Enhanced consistency in code organization.
+- Improved discoverability of test doubles.
+- Clearer distinction between production and test code.
+- Simplified maintenance of test implementations.
+
+---
+
 ## 2. Remove Artifacts serialization support when compiling to WebAssembly
 
 date: 2025-02-26

diff --git a/internal/cardano-node/mithril-cardano-node-chain/Cargo.toml b/internal/cardano-node/mithril-cardano-node-chain/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mithril-cardano-node-chain"
-version = "0.1.4"
+version = "0.1.5"
 authors.workspace = true
 documentation.workspace = true
 edition.workspace = true

diff --git a/internal/cardano-node/mithril-cardano-node-chain/src/test/double/chain_observer.rs b/internal/cardano-node/mithril-cardano-node-chain/src/test/double/chain_observer.rs
@@ -212,7 +212,7 @@ impl ChainObserver for FakeChainObserver {
 
 #[cfg(test)]
 mod tests {
-    use mithril_common::test_utils::fake_data;
+    use mithril_common::test_utils::{double::Dummy, fake_data};
 
     use super::*;
 

diff --git a/internal/mithril-dmq/Cargo.toml b/internal/mithril-dmq/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "mithril-dmq"
 description = "Mechanisms to publish and consume messages of a 'Decentralized Message Queue network' through a DMQ node"
-version = "0.1.4"
+version = "0.1.5"
 authors.workspace = true
 documentation.workspace = true
 edition.workspace = true

diff --git a/internal/mithril-dmq/src/message.rs b/internal/mithril-dmq/src/message.rs
@@ -94,6 +94,7 @@ mod tests {
     use mithril_common::{
         crypto_helper::{KesSignerFake, TryToBytes},
         entities::{BlockNumber, ChainPoint, TimePoint},
+        test_utils::double::Dummy,
     };
 
     use super::*;

diff --git a/internal/mithril-dmq/src/publisher/pallas.rs b/internal/mithril-dmq/src/publisher/pallas.rs
@@ -82,7 +82,6 @@ impl<M: TryToBytes + Debug + Sync + Send> DmqPublisher<M> for DmqPublisherPallas
 
 #[cfg(all(test, unix))]
 mod tests {
-
     use std::{fs, sync::Arc};
 
     use pallas_network::miniprotocols::{
@@ -91,7 +90,11 @@ mod tests {
     use tokio::{net::UnixListener, task::JoinHandle};
 
     use mithril_cardano_node_chain::test::double::FakeChainObserver;
-    use mithril_common::{crypto_helper::KesSignerFake, current_function, test_utils::TempDir};
+    use mithril_common::{
+        crypto_helper::KesSignerFake,
+        current_function,
+        test_utils::{TempDir, double::Dummy},
+    };
 
     use crate::{test::payload::DmqMessageTestPayload, test_tools::TestLogger};
 

diff --git a/internal/mithril-dmq/src/test/payload.rs b/internal/mithril-dmq/src/test/payload.rs
@@ -3,6 +3,7 @@ use std::fmt::Debug;
 use mithril_common::{
     StdResult,
     crypto_helper::{TryFromBytes, TryToBytes},
+    test_utils::double::Dummy,
 };
 
 /// A test message payload for the DMQ.
@@ -18,9 +19,11 @@ impl DmqMessageTestPayload {
             message: bytes.to_vec(),
         }
     }
+}
 
+impl Dummy for DmqMessageTestPayload {
     /// Creates a dummy `DmqMessageTestPayload` with a predefined message.
-    pub fn dummy() -> Self {
+    fn dummy() -> Self {
         Self {
             message: b"dummy message".to_vec(),
         }

diff --git a/internal/mithril-era/Cargo.toml b/internal/mithril-era/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mithril-era"
-version = "0.1.2"
+version = "0.1.3"
 authors.workspace = true
 documentation.workspace = true
 edition.workspace = true

diff --git a/internal/mithril-era/src/adapters/bootstrap.rs b/internal/mithril-era/src/adapters/bootstrap.rs
@@ -22,6 +22,8 @@ impl EraReaderAdapter for BootstrapAdapter {
 
 #[cfg(test)]
 mod tests {
+    use mithril_common::test_utils::double::Dummy;
+
     use super::*;
 
     #[tokio::test]

diff --git a/internal/mithril-era/src/adapters/dummy.rs b/internal/mithril-era/src/adapters/dummy.rs
@@ -40,6 +40,7 @@ impl EraReaderAdapter for DummyAdapter {
 #[cfg(test)]
 mod tests {
     use mithril_common::entities::{Epoch, SupportedEra};
+    use mithril_common::test_utils::double::Dummy;
 
     use super::*;
 

diff --git a/internal/mithril-era/src/adapters/file.rs b/internal/mithril-era/src/adapters/file.rs
@@ -30,7 +30,7 @@ impl EraReaderAdapter for FileAdapter {
 #[cfg(test)]
 mod tests {
     use mithril_common::entities::{Epoch, SupportedEra};
-    use mithril_common::test_utils::TempDir;
+    use mithril_common::test_utils::{TempDir, double::Dummy};
 
     use super::*;
 

diff --git a/internal/mithril-era/src/era_checker.rs b/internal/mithril-era/src/era_checker.rs
@@ -55,6 +55,8 @@ impl ApiVersionDiscriminantSource for EraChecker {
 
 #[cfg(test)]
 mod tests {
+    use mithril_common::test_utils::double::Dummy;
+
     use super::*;
 
     #[test]

diff --git a/internal/mithril-era/src/era_reader.rs b/internal/mithril-era/src/era_reader.rs
@@ -176,6 +176,8 @@ impl EraReader {
 
 #[cfg(test)]
 mod tests {
+    use mithril_common::test_utils::double::Dummy;
+
     use super::super::adapters::EraReaderDummyAdapter as DummyAdapter;
     use super::*;
 

diff --git a/internal/signed-entity/mithril-signed-entity-preloader/Cargo.toml b/internal/signed-entity/mithril-signed-entity-preloader/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mithril-signed-entity-preloader"
-version = "0.0.7"
+version = "0.0.8"
 description = "A preload mechanism for Cardano Transaction signed entity."
 authors = { workspace = true }
 edition = { workspace = true }

diff --git a/internal/signed-entity/mithril-signed-entity-preloader/src/cardano_transactions_preloader.rs b/internal/signed-entity/mithril-signed-entity-preloader/src/cardano_transactions_preloader.rs
@@ -128,6 +128,7 @@ mod tests {
 
     use mithril_cardano_node_chain::test::double::FakeChainObserver;
     use mithril_common::entities::{BlockNumber, ChainPoint, TimePoint};
+    use mithril_common::test_utils::double::Dummy;
 
     use crate::test_tools::TestLogger;
 

diff --git a/internal/tests/mithril-api-spec/Cargo.toml b/internal/tests/mithril-api-spec/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mithril-api-spec"
-version = "0.1.1"
+version = "0.1.2"
 authors.workspace = true
 documentation.workspace = true
 edition.workspace = true

diff --git a/internal/tests/mithril-api-spec/src/apispec.rs b/internal/tests/mithril-api-spec/src/apispec.rs
@@ -343,7 +343,7 @@ mod tests {
 
     use mithril_common::entities;
     use mithril_common::messages::{AggregatorFeaturesMessage, SignerMessagePart};
-    use mithril_common::test_utils::{TempDir, fake_data};
+    use mithril_common::test_utils::{TempDir, double::Dummy, fake_data};
 
     use super::*;
 

diff --git a/mithril-aggregator/Cargo.toml b/mithril-aggregator/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mithril-aggregator"
-version = "0.7.74"
+version = "0.7.75"
 description = "A Mithril Aggregator server"
 authors = { workspace = true }
 edition = { workspace = true }

diff --git a/mithril-aggregator/src/artifact_builder/cardano_database_artifacts/ancillary.rs b/mithril-aggregator/src/artifact_builder/cardano_database_artifacts/ancillary.rs
@@ -206,7 +206,7 @@ impl AncillaryArtifactBuilder {
 mod tests {
     use std::path::PathBuf;
 
-    use mithril_common::test_utils::{TempDir, assert_equivalent};
+    use mithril_common::test_utils::{TempDir, assert_equivalent, double::Dummy};
 
     use crate::services::{DumbSnapshotter, MockSnapshotter};
     use crate::test_tools::TestLogger;

diff --git a/mithril-aggregator/src/artifact_builder/cardano_database_artifacts/digest.rs b/mithril-aggregator/src/artifact_builder/cardano_database_artifacts/digest.rs
@@ -299,7 +299,7 @@ mod tests {
         current_function,
         entities::{CardanoDbBeacon, CompressionAlgorithm},
         messages::{CardanoDatabaseDigestListItemMessage, CardanoDatabaseDigestListMessage},
-        test_utils::{TempDir, assert_equivalent},
+        test_utils::{TempDir, assert_equivalent, double::Dummy},
     };
 
     use crate::{

diff --git a/mithril-aggregator/src/artifact_builder/mithril_stake_distribution.rs b/mithril-aggregator/src/artifact_builder/mithril_stake_distribution.rs
@@ -38,7 +38,10 @@ impl ArtifactBuilder<Epoch, MithrilStakeDistribution> for MithrilStakeDistributi
 
 #[cfg(test)]
 mod tests {
-    use mithril_common::{crypto_helper::ProtocolParameters, test_utils::fake_data};
+    use mithril_common::{
+        crypto_helper::ProtocolParameters,
+        test_utils::{double::Dummy, fake_data},
+    };
     use std::sync::Arc;
     use tokio::sync::RwLock;
 

diff --git a/mithril-aggregator/src/database/query/open_message/insert_or_replace_open_message.rs b/mithril-aggregator/src/database/query/open_message/insert_or_replace_open_message.rs
@@ -34,6 +34,7 @@ impl Query for InsertOrReplaceOpenMessageQuery {
 
 #[cfg(test)]
 mod tests {
+    use mithril_common::test_utils::double::Dummy;
     use mithril_persistence::sqlite::ConnectionExtensions;
 
     use crate::database::query::GetOpenMessageQuery;

diff --git a/mithril-aggregator/src/database/record/immutable_file_digest.rs b/mithril-aggregator/src/database/record/immutable_file_digest.rs
@@ -19,15 +19,6 @@ impl ImmutableFileDigestRecord {
         let aliases = SourceAlias::new(&[("{:immutable_file_digest:}", table)]);
         Self::get_projection().expand(aliases)
     }
-
-    #[cfg(test)]
-    /// Create a dumb ImmutableFileDigestRecord instance mainly for test purposes
-    pub fn dummy() -> Self {
-        Self {
-            immutable_file_name: "123.chunk".to_string(),
-            digest: "dummy_digest".to_string(),
-        }
-    }
 }
 
 impl SqLiteEntity for ImmutableFileDigestRecord {

diff --git a/mithril-aggregator/src/database/record/open_message.rs b/mithril-aggregator/src/database/record/open_message.rs
@@ -43,25 +43,6 @@ impl OpenMessageRecord {
     pub fn new_id() -> Uuid {
         Uuid::new_v4()
     }
-
-    #[cfg(test)]
-    /// Create a dumb OpenMessage instance mainly for test purposes
-    pub fn dummy() -> Self {
-        let beacon = mithril_common::test_utils::fake_data::beacon();
-        let epoch = beacon.epoch;
-        let signed_entity_type = SignedEntityType::CardanoImmutableFilesFull(beacon);
-
-        Self {
-            open_message_id: Uuid::parse_str("193d1442-e89b-43cf-9519-04d8db9a12ff").unwrap(),
-            epoch,
-            signed_entity_type,
-            protocol_message: ProtocolMessage::new(),
-            is_certified: false,
-            is_expired: false,
-            created_at: Utc::now(),
-            expires_at: None,
-        }
-    }
 }
 
 impl SqLiteEntity for OpenMessageRecord {

diff --git a/mithril-aggregator/src/database/repository/epoch_settings_store.rs b/mithril-aggregator/src/database/repository/epoch_settings_store.rs
@@ -92,6 +92,8 @@ impl EpochPruningTask for EpochSettingsStore {
 
 #[cfg(test)]
 mod tests {
+    use mithril_common::test_utils::double::Dummy;
+
     use crate::database::test_helper::{insert_epoch_settings, main_db_connection};
 
     use super::*;

diff --git a/mithril-aggregator/src/database/repository/open_message_repository.rs b/mithril-aggregator/src/database/repository/open_message_repository.rs
@@ -140,6 +140,7 @@ impl OpenMessageStorer for OpenMessageRepository {
 #[cfg(test)]
 mod tests {
     use mithril_common::entities::{BlockNumber, CardanoDbBeacon};
+    use mithril_common::test_utils::double::Dummy;
 
     use crate::database::record::SingleSignatureRecord;
     use crate::database::test_helper::{