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My goal is to write a test case to simulate my contract inside populus. I observe that each transaction()(even it is a empty function call) will increment block number as one no matter what.

[Q] As we know in a single block there could be multiple transactions. Is it possible to have multiple transactions in a single block, inside the test case of populus?

test.py:

blkArrayIndex =  0;
gasUsed       = [];
blockNumber   = [];

set_txn_hash     = my_contract.transact().dummy(); #this is a dummy transaction.
contract_address = unmigrated_chain.wait.for_receipt(set_txn_hash)

gasUsed.append( contract_address["gasUsed"] );
blockNumber.append( contract_address["blockNumber"] );
blkArrayIndex = blkArrayIndex + 1;

set_txn_hash     = my_contract.transact().dummy(); #added line.#
set_txn_hash     = my_contract.transact().dummy(); #added line.#
set_txn_hash     = my_contract.transact().dummy(); #added line.#
set_txn_hash     = my_contract.transact().dummy(); #this is a dummy transaction.
contract_address = unmigrated_chain.wait.for_receipt(set_txn_hash);

gasUsed.append( contract_address["gasUsed"] );
blockNumber.append( contract_address["blockNumber"] );
blkArrayIndex = blkArrayIndex + 1;

for j in range(0, blkArrayIndex):
    print '%s:%d |%s: %d' % ("gasUsed", gasUsed[j], "blockNumber", blockNumber[j])

Output (without added lines):

gasUsed:222648 |blockNumber: 4
gasUsed:290051 |blockNumber: 5

Output (when new lines are added): block number changed from 5 to 8.

gasUsed:222648|blockNumber: 4
gasUsed:350051|blockNumber: 8 <= after the added lines I want block number as 5 instead of 8.

1 Answer 1

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Having number of transactions in a block is possible but doing it manually is not possible, Block is created in 2 situations,

1.Time out period is reached.

There is a time out period to create a block (the exact time out period is unknown to me, may be 1 or 2 seconds), the transaction made in-between this timeout period are kept under a single block.

2.Max Limitation Reached

When we reach the max limitation of transactions to be contained in a single block(max limitation is unknown to me) before the time out reached , a new block is created and the transactions done after that are registered in new block

I think you are doing single transaction at a time and before doing another transaction the time out is getting expired, try doing multiple transactions at a time

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