add threshold for splitting stake too

crates/sui-framework/docs/staking_pool.md

@@ -343,6 +343,15 @@ A self-custodial object holding the staked SUI tokens.
 
 
 
+<a name="0x3_staking_pool_EStakedSuiBelowThreshold"></a>
+
+
+
+<pre><code><b>const</b> <a href="staking_pool.md#0x3_staking_pool_EStakedSuiBelowThreshold">EStakedSuiBelowThreshold</a>: u64 = 18;
+</code></pre>
+
+
+
 <a name="0x3_staking_pool_ETokenBalancesDoNotMatchExchangeRate"></a>
 
 
@@ -397,6 +406,16 @@ A self-custodial object holding the staked SUI tokens.
 
 
 
+<a name="0x3_staking_pool_MIN_STAKING_THRESHOLD"></a>
+
+StakedSui objects cannot be split to below this amount.
+
+
+<pre><code><b>const</b> <a href="staking_pool.md#0x3_staking_pool_MIN_STAKING_THRESHOLD">MIN_STAKING_THRESHOLD</a>: u64 = 1000000000;
+</code></pre>
+
+
+
 <a name="0x3_staking_pool_new"></a>
 
 ## Function `new`
@@ -1049,7 +1068,7 @@ Split the given StakedSui to the two parts, one with principal <code>split_amoun
 transfer the newly split part to the sender address.
 
 
-<pre><code><b>public</b> entry <b>fun</b> <a href="staking_pool.md#0x3_staking_pool_split_staked_sui">split_staked_sui</a>(c: &<b>mut</b> <a href="staking_pool.md#0x3_staking_pool_StakedSui">staking_pool::StakedSui</a>, split_amount: u64, ctx: &<b>mut</b> <a href="_TxContext">tx_context::TxContext</a>)
+<pre><code><b>public</b> entry <b>fun</b> <a href="staking_pool.md#0x3_staking_pool_split_staked_sui">split_staked_sui</a>(stake: &<b>mut</b> <a href="staking_pool.md#0x3_staking_pool_StakedSui">staking_pool::StakedSui</a>, split_amount: u64, ctx: &<b>mut</b> <a href="_TxContext">tx_context::TxContext</a>)
 </code></pre>
 
 
@@ -1058,8 +1077,14 @@ transfer the newly split part to the sender address.
 <summary>Implementation</summary>
 
 
-<pre><code><b>public</b> entry <b>fun</b> <a href="staking_pool.md#0x3_staking_pool_split_staked_sui">split_staked_sui</a>(c: &<b>mut</b> <a href="staking_pool.md#0x3_staking_pool_StakedSui">StakedSui</a>, split_amount: u64, ctx: &<b>mut</b> TxContext) {
-    <a href="_transfer">transfer::transfer</a>(<a href="staking_pool.md#0x3_staking_pool_split">split</a>(c, split_amount, ctx), <a href="_sender">tx_context::sender</a>(ctx));
+<pre><code><b>public</b> entry <b>fun</b> <a href="staking_pool.md#0x3_staking_pool_split_staked_sui">split_staked_sui</a>(stake: &<b>mut</b> <a href="staking_pool.md#0x3_staking_pool_StakedSui">StakedSui</a>, split_amount: u64, ctx: &<b>mut</b> TxContext) {
+    <b>let</b> original_amount = <a href="_value">balance::value</a>(&stake.principal);
+    <b>assert</b>!(split_amount &lt;= original_amount, <a href="staking_pool.md#0x3_staking_pool_EInsufficientSuiTokenBalance">EInsufficientSuiTokenBalance</a>);
+    <b>let</b> remaining_amount = original_amount - split_amount;
+    // Both resulting parts should have at least <a href="staking_pool.md#0x3_staking_pool_MIN_STAKING_THRESHOLD">MIN_STAKING_THRESHOLD</a>.
+    <b>assert</b>!(remaining_amount &gt;= <a href="staking_pool.md#0x3_staking_pool_MIN_STAKING_THRESHOLD">MIN_STAKING_THRESHOLD</a>, <a href="staking_pool.md#0x3_staking_pool_EStakedSuiBelowThreshold">EStakedSuiBelowThreshold</a>);
+    <b>assert</b>!(split_amount &gt;= <a href="staking_pool.md#0x3_staking_pool_MIN_STAKING_THRESHOLD">MIN_STAKING_THRESHOLD</a>, <a href="staking_pool.md#0x3_staking_pool_EStakedSuiBelowThreshold">EStakedSuiBelowThreshold</a>);
+    <a href="_transfer">transfer::transfer</a>(<a href="staking_pool.md#0x3_staking_pool_split">split</a>(stake, split_amount, ctx), <a href="_sender">tx_context::sender</a>(ctx));
 }
 </code></pre>
 

crates/sui-framework/docs/validator_set.md

@@ -351,6 +351,15 @@ The epoch value corresponds to the first epoch this change takes place.
 ## Constants
 
 
+<a name="0x3_validator_set_MIN_STAKING_THRESHOLD"></a>
+
+
+
+<pre><code><b>const</b> <a href="validator_set.md#0x3_validator_set_MIN_STAKING_THRESHOLD">MIN_STAKING_THRESHOLD</a>: u64 = 1000000000;
+</code></pre>
+
+
+
 <a name="0x3_validator_set_EInvalidCap"></a>
 
 
@@ -495,15 +504,6 @@ The epoch value corresponds to the first epoch this change takes place.
 
 
 
-<a name="0x3_validator_set_MIN_STAKING_THRESHOLD"></a>
-
-
-
-<pre><code><b>const</b> <a href="validator_set.md#0x3_validator_set_MIN_STAKING_THRESHOLD">MIN_STAKING_THRESHOLD</a>: u64 = 1000000000;
-</code></pre>
-
-
-
 <a name="0x3_validator_set_new"></a>
 
 ## Function `new`

crates/sui-framework/packages/sui-system/sources/staking_pool.move

@@ -17,6 +17,9 @@ module sui_system::staking_pool {
     friend sui_system::validator;
     friend sui_system::validator_set;
 
+    /// StakedSui objects cannot be split to below this amount.
+    const MIN_STAKING_THRESHOLD: u64 = 1_000_000_000; // 1 SUI
+
     const EInsufficientPoolTokenBalance: u64 = 0;
     const EWrongPool: u64 = 1;
     const EWithdrawAmountCannotBeZero: u64 = 2;
@@ -35,6 +38,7 @@ module sui_system::staking_pool {
     const EPoolNotPreactive: u64 = 15;
     const EActivationOfInactivePool: u64 = 16;
     const EDelegationOfZeroSui: u64 = 17;
+    const EStakedSuiBelowThreshold: u64 = 18;
 
     /// A staking pool embedded in each validator struct in the system state object.
     struct StakingPool has key, store {
@@ -342,8 +346,14 @@ module sui_system::staking_pool {
 
     /// Split the given StakedSui to the two parts, one with principal `split_amount`,
     /// transfer the newly split part to the sender address.
-    public entry fun split_staked_sui(c: &mut StakedSui, split_amount: u64, ctx: &mut TxContext) {
-        transfer::transfer(split(c, split_amount, ctx), tx_context::sender(ctx));
+    public entry fun split_staked_sui(stake: &mut StakedSui, split_amount: u64, ctx: &mut TxContext) {
+        let original_amount = balance::value(&stake.principal);
+        assert!(split_amount <= original_amount, EInsufficientSuiTokenBalance);
+        let remaining_amount = original_amount - split_amount;
+        // Both resulting parts should have at least MIN_STAKING_THRESHOLD.
+        assert!(remaining_amount >= MIN_STAKING_THRESHOLD, EStakedSuiBelowThreshold);
+        assert!(split_amount >= MIN_STAKING_THRESHOLD, EStakedSuiBelowThreshold);
+        transfer::transfer(split(stake, split_amount, ctx), tx_context::sender(ctx));
     }
 
     /// Consume the staked sui `other` and add its value to `self`.

crates/sui-framework/packages/sui-system/tests/delegation_tests.move

@@ -105,6 +105,26 @@ module sui_system::stake_tests {
         test_scenario::end(scenario_val);
     }
 
+    #[test]
+    #[expected_failure(abort_code = staking_pool::EStakedSuiBelowThreshold)]
+    fun test_split_below_threshold() {
+        let scenario_val = test_scenario::begin(STAKER_ADDR_1);
+        let scenario = &mut scenario_val;
+        set_up_sui_system_state(scenario);
+        // Stake 2 SUI
+        governance_test_utils::stake_with(STAKER_ADDR_1, VALIDATOR_ADDR_1, 2, scenario);
+
+        test_scenario::next_tx(scenario, STAKER_ADDR_1);
+        {
+            let staked_sui = test_scenario::take_from_sender<StakedSui>(scenario);
+            let ctx = test_scenario::ctx(scenario);
+            // The remaining amount after splitting is below the threshold so this should fail.
+            staking_pool::split_staked_sui(&mut staked_sui, 1 * MIST_PER_SUI + 1, ctx);
+            test_scenario::return_to_sender(scenario, staked_sui);
+        };
+        test_scenario::end(scenario_val);
+    }
+
     #[test]
     fun test_add_remove_stake_flow() {
         let scenario_val = test_scenario::begin(VALIDATOR_ADDR_1);