Tutorials > Polkadot SDK > Parachains > Build Custom Pallet > Pallet …

…Unit Testing (#233)

* fix: wip

* fix: adding snippets

* fix: typo

* Apply suggestions from code review

Co-authored-by: 0xLucca <95830307+0xLucca@users.noreply.github.com>

* fix: updating mock runtime\

* fix: snippets comments

* fix: typo

* fix: closing expandable elements

* fix: overflow

* fix: overflow

* Update tutorials/polkadot-sdk/parachains/build-custom-pallet/pallet-unit-testing.md

Co-authored-by: Erin Shaben <eshaben@icloud.com>

* fix: feedback

* fix: clean up the add tutorial branch

* Update tutorials/polkadot-sdk/parachains/build-custom-pallet/pallet-unit-testing.md

Co-authored-by: Erin Shaben <eshaben@icloud.com>

---------

Co-authored-by: 0xLucca <95830307+0xLucca@users.noreply.github.com>
Co-authored-by: Erin Shaben <eshaben@icloud.com>

.husky/pre-commit

@@ -8,6 +8,7 @@ IGNORED_FILES=(
   ".snippets/code/develop/toolkit/parachains/spawn-chains/zombienet/write-tests/big-network-test.toml"
   ".snippets/code/develop/toolkit/parachains/spawn-chains/zombienet/write-tests/small-network-test.toml"
   ".snippets/code/develop/toolkit/parachains/spawn-chains/zombienet/write-tests/spawn-a-basic-chain-test.toml"
+  ".snippets/code/tutorials/polkadot-sdk/parachains/build-custom-pallet/pallet-unit-testing/cargo-dev-dependencies.toml"
 )
 
 # Normalize ignored files pattern

.snippets/code/tutorials/polkadot-sdk/parachains/build-custom-pallet/pallet-unit-testing/Cargo-dev-dependencies.toml

@@ -0,0 +1,10 @@
+[dependencies]
+...
+
+[dev-dependencies]
+sp-core = { workspace = true, default-features = true }
+sp-io = { workspace = true, default-features = true }
+sp-runtime = { workspace = true, default-features = true }
+
+[features]
+...

.snippets/code/tutorials/polkadot-sdk/parachains/build-custom-pallet/pallet-unit-testing/mock.rs

@@ -0,0 +1,52 @@
+use crate as pallet_custom;
+use frame_support::{derive_impl, parameter_types};
+use sp_runtime::BuildStorage;
+
+type Block = frame_system::mocking::MockBlock<Test>;
+
+#[frame_support::runtime]
+mod runtime {
+    #[runtime::runtime]
+    #[runtime::derive(
+        RuntimeCall,
+        RuntimeEvent,
+        RuntimeError,
+        RuntimeOrigin,
+        RuntimeFreezeReason,
+        RuntimeHoldReason,
+        RuntimeSlashReason,
+        RuntimeLockId,
+        RuntimeTask
+    )]
+    pub struct Test;
+
+    #[runtime::pallet_index(0)]
+    pub type System = frame_system::Pallet<Test>;
+
+    #[runtime::pallet_index(1)]
+    pub type CustomPallet = pallet_custom::Pallet<Test>;
+}
+
+// System pallet configuration
+#[derive_impl(frame_system::config_preludes::TestDefaultConfig)]
+impl frame_system::Config for Test {
+    type Block = Block;
+}
+
+// Custom pallet configuration
+parameter_types! {
+    pub const CounterMaxValue: u32 = 10;
+}
+
+impl pallet_custom::Config for Test {
+    type RuntimeEvent = RuntimeEvent;
+    type CounterMaxValue = CounterMaxValue;
+}
+
+// Test externalities initialization
+pub fn new_test_ext() -> sp_io::TestExternalities {
+    frame_system::GenesisConfig::<Test>::default()
+        .build_storage()
+        .unwrap()
+        .into()
+}

.snippets/code/tutorials/polkadot-sdk/parachains/build-custom-pallet/pallet-unit-testing/output.html

@@ -0,0 +1,24 @@
+<div id="termynal" data-termynal>
+  <span data-ty="input"><span class="file-path"></span>cargo test --package custom-pallet</span>
+  <pre>
+running 12 tests
+test mock::__construct_runtime_integrity_test::runtime_integrity_tests ... ok
+test mock::test_genesis_config_builds ... ok
+test test::set_counter_value_fails_for_max_value_exceeded ... ok
+test test::set_counter_value_fails_for_non_root ... ok
+test test::user_interactions_increment ... ok
+test test::it_works_for_increment ... ok
+test test::it_works_for_set_counter_value ... ok
+test test::it_works_for_decrement ... ok
+test test::increment_handles_overflow ... ok
+test test::decrement_fails_for_below_zero ... ok
+test test::increment_fails_for_max_value_exceeded ... ok
+test test::user_interactions_overflow ... ok
+test result: ok. 12 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.01s
+
+Doc-tests custom_pallet
+running 0 tests
+test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
+    </pre
+  >
+</div>