Fs check query

[filipsch]

@richierocks these changes would include a new function in sqlwhat, called check_query(), that allows you to run arbitrary sql statements after rerunning the student query, so you can verify whether UPDATEs, INSERTs etc happened correctly. Let me know what you think, if you have an opinion. The docs in sqlwhat/checks/check_funcs.py are most interesting for you.

[filipsch]

@richierocks, @hermansje and I have worked on an improved version. Basically, this is how you would now check whether running a query returns the same table after executing the student/solution code (that would contain INSERT statements, for example):

Ex().check_query('SELECT COUNT(*) FROM company').has_equal_value()

What this does, as mentioned before:

1. Run the solution submission + the query passed in check_query() in a transaction and fetch the result.
2. Run the student's submission + the query passed in check_query() in a transaction and fetch the result.
3. Create a 'child state' with this 'solution result' and 'student result' that you can chain off of with check_column() (if you want to further zoom in), has_equal_value() etc.
4. has_equal_value() will then compare these results.

Thus, in a sense, check_query() is 'overriding' the query result that the student's submission and solution generated and that is stored in Ex().

Looks good?

[richierocks]

One thing to note is that is you want to check arbitrary expressions, the syntax is pretty different across languages.

R:

ex() %>% check_expr('some code') %>% check_result() %>% check_equal()

Shell:

Ex().has_expr_output(expr='some command', output='some output')

SQL:

Ex().check_query('SELECT something').has_equal_value()

@hermansje figuring out how to synchronize the check syntax across the *what packages would be a good long term project.

[klmedeiros]

I'd like to second what @richierocks has said above. As someone who frequently switches back and forth between languages writing SCTs, it gets difficult with the inconsistency in function names.

[filipsch]

@klmedeiros @richierocks I understand your concerns, and @hermansje and I talked about it at length. Before I go, I will make sure to list out exactly which functions are used where and how, and Jeroen can then think about how things can be made more consistent.

However, some thoughts:

• R, Python, Shell and SQL are different languages, with different ways of working. This can ask for different ways of doing the SCT syntax. We shouldn't force everything to be the same just for its sake.
• We made decisions in the past that were not consistent or did not make sense, but that shouldn't stop us from improving in the future.
• The example that @richierocks includes of Shell uses a different name on purpose, because it does not do the same thing as has_equal_value(). The latter is running both the solution and the student code, while has_expr_output() only runs student code.

[klmedeiros]

@filipsch Thank you for the context in your response, that's very helpful for me!