feat: command to test DB engine specs

[betodealmeida]

SUMMARY

This PR adds a README for DB engine specs, describing all their features and functionality. It also adds a new command to test DB engine specs, SQLAlchemy dialects, and database connections:

$ superset test-db sqlite://
Loaded your LOCAL configuration at [/Users/beto/Projects/github/superset/superset_config.py]
Collecting additional connection information...
SQLAlchemy URI: sqlite://
> Do you want to configure connection arguments? [y/N] 
Checking for a DB engine spec...
👍 Found DB engine spec: SQLite
About the database:
  - Method used to apply LIMIT to queries: FORCE_LIMIT
    - FORCE_LIMIT: modifies the query, replacing an existing LIMIT or adding a new one
    - WRAP_SQL: wraps the original query in a SELECT * with a LIMIT
    - FETCH_MANY: runs the query unmodified but fetchs only LIMIT rows from the cursor
  - Method used to limit the rows in the subquery: FORCE_LIMIT
  - Supports JOINs: True
  - Supports subqueries: True
  - Allows aliases in the SELECT statement: True
  - Allows referencing aliases in the ORDER BY statement: True
  - Supports secondary time columns: False
  - Allows ommiting time filters from inline GROUP BYs: False
  - Able to use source column when an alias overshadows it: False
  - Allows aggregations in ORDER BY not present in the SELECT: True
  - Allows expressions in ORDER BY: False
  - Allows CTE as a subquery: True
  - Allows LIMIT clause (instead of TOP): True
  - Maximum column name: None
  - Allows comments: True
  - Colons must be escaped: True
Checking for basic features...
Supported time grains:
  - SECOND: True (+1)
  - FIVE_SECONDS: True (+1)
  - THIRTY_SECONDS: True (+1)
  - MINUTE: True (+1)
  - FIVE_MINUTES: True (+1)
  - TEN_MINUTES: True (+1)
  - FIFTEEN_MINUTES: True (+1)
  - THIRTY_MINUTES: True (+1)
  - HALF_HOUR: True (+1)
  - HOUR: True (+1)
  - SIX_HOURS: True (+1)
  - DAY: True (+1)
  - WEEK: True (+1)
  - WEEK_STARTING_SUNDAY: True (+1)
  - WEEK_STARTING_MONDAY: True (+1)
  - WEEK_ENDING_SATURDAY: True (+1)
  - WEEK_ENDING_SUNDAY: True (+1)
  - MONTH: True (+1)
  - QUARTER: True (+1)
  - QUARTER_YEAR: True (+1)
  - YEAR: True (+1)
Masks/unmasks encrypted_extra: False
Has column type mappings: False
Returns a list of function names: True (+10)
Checking for nice-to-have features...
Supports user impersonation: False
Support file upload: True (+10)
Returns extra table metadata: False
Maps driver exceptions to Superset exceptions: False
Parses error messages and returns Superset errors: False
Supports changing the schema per-query: False
Supports catalogs: False
Supports changing the catalog per-query: False
Can be connected thru an SSH tunnel: False
Allows query to be canceled: False
Returns additional metrics on dataset creation: False
Supports querying the latest partition only: False
Checking for advanced features...
Expands complex types (arrays, structs) into rows/columns: False
Supports query cost estimation: False
Supports validating SQL before running query: False
Overall score: 41/201

Testing the SQLAlchemy dialect...
Checking functions used by the inspector...
  - get_schema_names: True
  - get_table_names: True
  - get_view_names: True
  - get_indexes: True
  - get_table_comment: True
  - get_columns: True
  - get_unique_constraints: True
  - get_check_constraints: True
  - get_pk_constraint: True
  - get_foreign_keys: True
Checking dialect attributes...
  - dbapi: sqlite3.dbapi2
  - name: sqlite
  - driver: pysqlite
  - supports_multivalues_insert: True
Supports do_ping: True
Can quote identifiers: True
Doesn't require name normalization: True

Testing the database connectivity...
👍 Connected successfully!
Checking that we can run queries...
sql> SELECT 1;
> 1
Checking that we can create tables...
Tables created!
Checking that we can insert data...
sql> INSERT INTO user (user_name, email_address, nickname) VALUES ('beto', 'beto@example.org', 'Beto')
Checking that we can read data...
sql> SELECT user.user_id, user.user_name, user.email_address, user.nickname 
FROM user 
WHERE user.user_name = 'beto'
> [(1, 'beto', 'beto@example.org', 'Beto')]
Checking that we can drop tables...
Done!
Running engine-specific tests...
Testing datetime support...
Creating a table with a timestamp column...
Table created!
Inserting timestamp value...
Reading timestamp value...
👍 Succcess!

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #24918 (13154e7) into master (eb7c145) will increase coverage by 1.54%.
Report is 2 commits behind head on master.
The diff coverage is 6.06%.

❗ Current head 13154e7 differs from pull request most recent head 478fbe0. Consider uploading reports for the commit 478fbe0 to get more accurate results

@@            Coverage Diff             @@
##           master   #24918      +/-   ##
==========================================
+ Coverage   67.22%   68.77%   +1.54%     
==========================================
  Files        1906     1908       +2     
  Lines       74134    74390     +256     
  Branches     8208     8208              
==========================================
+ Hits        49840    51165    +1325     
+ Misses      22171    21102    -1069     
  Partials     2123     2123              

Flag	Coverage Δ
hive	53.82% <6.06%> (-0.36%)	⬇️
mysql	78.67% <6.06%> (-0.55%)	⬇️
postgres	78.77% <6.06%> (-0.55%)	⬇️
presto	53.72% <6.06%> (?)
python	82.79% <6.06%> (+3.13%)	⬆️
sqlite	77.35% <6.06%> (-0.54%)	⬇️
unit	54.69% <6.06%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
.../src/dashboard/components/gridComponents/Chart.jsx	59.25% <ø> (+0.99%)	⬆️
superset/cli/test_db.py	0.00% <0.00%> (ø)
superset/db_engine_specs/sqlite.py	97.22% <ø> (+2.77%)	⬆️
superset/db_engine_specs/lib.py	21.73% <21.73%> (ø)
superset/db_engine_specs/base.py	91.02% <100.00%> (+8.68%)	⬆️

... and 99 files with indirect coverage changes

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[villebro]

Very nice, this will be a big help for people developing new specs! Just a few minor comments, LGTM