blockchain: move loop check

blockchain: add setHead / iterator tests

blockchain: remove unnecessary iterator logic

Author: jochem-brouwer

packages/blockchain/src/index.ts

@@ -736,7 +736,7 @@ export default class Blockchain implements BlockchainInterface {
    *
    * @param name - Name of the state root head
    * @param onBlock - Function called on each block with params (block, reorg)
-   * @param maxBlocks - How many blocks to run. By default, run all blocks in the canonical chain.
+   * @param maxBlocks - How many blocks to run. By default, run all unprocessed blocks in the canonical chain.
    */
   async iterator(name: string, onBlock: OnBlock, maxBlocks?: number) {
     return this._iterator(name, onBlock, maxBlocks)
@@ -754,12 +754,15 @@ export default class Blockchain implements BlockchainInterface {
         return
       }
 
+      if (maxBlocks && maxBlocks < 0) {
+        throw 'If maxBlocks is provided, it has to be a non-negative number'
+      }
+
       const number = await this.dbManager.hashToNumber(blockHash)
       const blockNumber = number.addn(1)
       let blocksRanCounter = 0
 
-      // eslint-disable-next-line no-constant-condition
-      while (true) {
+      while (maxBlocks !== blocksRanCounter) {
         try {
           const block = await this._getBlock(blockNumber)
 
@@ -773,9 +776,6 @@ export default class Blockchain implements BlockchainInterface {
           await onBlock(block, reorg)
           blockNumber.iaddn(1)
           blocksRanCounter++
-          if (maxBlocks && blocksRanCounter == maxBlocks) {
-            break
-          }
         } catch (error) {
           if (error.type !== 'NotFoundError') {
             throw error
@@ -794,7 +794,6 @@ export default class Blockchain implements BlockchainInterface {
    * @param tag - The tag to save the headHash to
    * @param headHash - The head hash to save
    */
-
   async setHead(tag: string, headHash: Buffer) {
     await this.initAndLock<void>(async () => {
       this._heads[tag] = headHash

packages/blockchain/test/index.ts

@@ -348,6 +348,99 @@ tape('blockchain test', (t) => {
     st.end()
   })
 
+  t.test(
+    'should iterate through maxBlocks blocks if maxBlocks parameter is provided',
+    async (st) => {
+      const { blockchain, blocks, error } = await generateBlockchain(25)
+      st.error(error, 'no error')
+      let i = 0
+      await blockchain.iterator(
+        'test',
+        (block: Block) => {
+          if (block.hash().equals(blocks[i + 1].hash())) {
+            i++
+          }
+        },
+        5
+      )
+      st.equals(i, 5)
+      st.end()
+    }
+  )
+
+  t.test(
+    'should iterate through 0 blocks in case 0 maxBlocks parameter is provided',
+    async (st) => {
+      const { blockchain, blocks, error } = await generateBlockchain(25)
+      st.error(error, 'no error')
+      let i = 0
+      await blockchain
+        .iterator(
+          'test',
+          (block: Block) => {
+            if (block.hash().equals(blocks[i + 1].hash())) {
+              i++
+            }
+          },
+          0
+        )
+        .catch(() => {
+          st.fail('Promise cannot throw when running 0 blocks')
+        })
+      st.equals(i, 0)
+      st.end()
+    }
+  )
+
+  t.test('should throw on a negative maxBlocks parameter in iterator', async (st) => {
+    const { blockchain, blocks, error } = await generateBlockchain(25)
+    st.error(error, 'no error')
+    let i = 0
+    await blockchain
+      .iterator(
+        'test',
+        (block: Block) => {
+          if (block.hash().equals(blocks[i + 1].hash())) {
+            i++
+          }
+        },
+        -1
+      )
+      .catch(() => {
+        st.end()
+      })
+    // Note: if st.end() is not called (Promise did not throw), then this test fails, as it does not end.
+  })
+
+  t.test('should test setHead method', async (st) => {
+    const { blockchain, blocks, error } = await generateBlockchain(25)
+    st.error(error, 'no error')
+
+    const headBlockIndex = 5
+
+    const headHash = blocks[headBlockIndex].hash()
+    await blockchain.setHead('myHead', headHash)
+    const currentHeadBlock = await blockchain.getHead('myHead')
+
+    st.ok(headHash.equals(currentHeadBlock.hash()), 'head hash equals the provided head hash')
+
+    let i = 0
+    // check that iterator starts from this head block
+    await blockchain.iterator(
+      'myHead',
+      (block: Block) => {
+        if (block.hash().equals(blocks[headBlockIndex + 1].hash())) {
+          i++
+        }
+      },
+      5
+    )
+
+    st.equals(i, 1)
+
+    st.end()
+  })
+
   t.test('should catch iterator func error', async (st) => {
     const { blockchain, error } = await generateBlockchain(25)
     st.error(error, 'no error')