Lab 2

Info

This lab (continues on Lab 1) and will teach you how to:

• run code coverage to see how much code is covered by unit-tests
• auto generate C# Interfaces and Service classes from the SmartContract
• deploy the SmartContract using a bare-bone console application to your local Ethereum Blockchain using GETH

What is Go-Ethereum (GETH)

Go Ethereum is one of the three original implementations (along with C++ and Python) of the Ethereum protocol. It is written in Go, fully open source and licensed under the GNU LGPL v3. See also geth.ethereum.org.

If you have some generic or detailed questions, please feel free to ask these at mStack colleagues.

Folder structure

• Solidity: folder for the SmartContracts written in Solidity and unit-tests written in javascript.
• ConsoleApp: folder for the ConsoleApp (C#).

Details

This lab contains two simple SmartContracts:

• SimpleStorageContract this contract can store and retrieve number and string values
• MultiplyContract this contract is initialized with a default multiply factor and can do some basic multiplications

Steps

Execute the following steps in order to follow this Lab.

Step 1

Go to the terminal in VS Code and type:

• cd Lab 2
• cd Solidity
• npm i (to install all required node packages)

Step 2

Go to the terminal in VS Code and type:

• npm test, this command will use Truffle run the test. Note that also the linter is run.

All tests should pass.

Step 3

Go to the terminal in VS Code and type: npm run coverage, this command will start a TestRPC (a local in-memory Ethereum Virtual Machine in JavaScript) and Solidity Coverage to determine the unit-test code coverage.

In the console output, you should see something like:

[Coverage] ----------------------------|----------|----------|----------|----------|----------------|
[Coverage] File                        |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
[Coverage] ----------------------------|----------|----------|----------|----------|----------------|
[Coverage]  contracts\                 |    77.78 |       50 |    83.33 |    77.78 |                |
[Coverage]   SimpleStorageContract.sol |    77.78 |       50 |    83.33 |    77.78 |          18,37 |
[Coverage] ----------------------------|----------|----------|----------|----------|----------------|
[Coverage] All files                   |    77.78 |       50 |    83.33 |    77.78 |                |
[Coverage] ----------------------------|----------|----------|----------|----------|----------------|

A more detailed code coverage HTML file is generated at Lab 2\Solidity\coverage\index.html. Open this file in an interner browser. This should look like:

Click the contracts link and drill down to the contract file:

Step 4

Add some more tests to increase the code coverage to 100% by updating the unit-tests in Lab 2\Solidity\test\SimpleStorageTests.spec.js.

Rerun the test with npm run coverage to verify that the coverage is 100%.

Step 5

Now that the SmartContract has passed the linter, unit-tests and code-coverage, it's time to start coding in c# to execute some calls on this contract.

Run the command npm run build to generate C# Interfaces and Service classes from this SmartContract. You should see this output in the console:

Compiling contracts
SimpleStorageContract: generate ABI and ByteCode
SimpleStorageContract: generate C# helper classes
SimpleStorageContract: generate C# interfaces
SimpleStorageContract: generate C# implementations

Step 6

Now open a new command terminal in Visual Code, and type:

• cd Lab 2
• cd ConsoleApp
• dotnet build (if all is fine, a restore should be done and the build should complete with 0 errors.)

Step 7

Now go to the location where the github project is downloaded or clone and double click the Tools\testchain\startheth.bat file.

This command will start a local instance from Etherum VM using GO-Eth.

Note that running this can take up some CPU and Memory, so when you're done testing (and before each test with the console-app), just close the cmd window.

Step 8

Go to the command terminal in Visual Code, and type:

• dotnet run to run the ConsoleApp

If all is configured correctly, you should see output like:

Blockchain - Ethereum - ConsoleApp
--------------------------------------------------------------------------------
Deploying contract (can take some time)
Deploying contract done, address = 0xd0828aeb00e4db6813e2f330318ef94d2bba2f60

This means that the contract was deployed successfully and is assigned to that address 0xd0828aeb00e4db6813e2f330318ef94d2bba2f60.

No extra code is executed yet because all TODO's are still commented. In the next steps C# will be written to execute methods on the contract.

Step 9

Open the file Lab 2\ConsoleApp\Program.cs in Visual Code.

• enable the TODO 1 code. This code executes the function SetNumberAsync as a transaction, wrapping this in a ExecuteTransactionAsync(...) call
• also enable TODO 2 to print out the persisted value to the console logging
• enable TODO 3 and TODO 4 to store and retrieve a string from the SmartContract
• Run the ConsoleApp dotnet run and the output should lool like:

Deploying contract (can take some time)
Deploying contract done, address = 0x2e5f6d7138ce653ec0e47101e1c03a7e42d414f2
The stored number value is '10'.
The stored string value is 'mstack.nl test'.

Step 10

• Keep the startgeth.bat running
• Remember the address where the contract was deployed in the previous step
• At the TODO 0 change the value from deployNewContract from true to false
• Also change the value from contractAddress from null to the Contract address you remembered
• Comment the code at again at TODO 1 and TODO 3 to make sure you don't set any values
• Rerun the ConsoleApp dotnet run to see that the values which were stored in Step 9 are still persisted in the contract

Step 11

Done.