Brought into line with new data provider structure.

Updated to more comprehensively reflect the specified requirements. Also tweaked some data types.

Fixed typo in output.

Removed Suppliers_Code from Assembly and Order_line tables and data fixtures.

- Fixed length of phone numbers in test data. ...

- Brought into line with new data provider structure.

Added some legal phone numbers.

- Brought into line with new data provider structure. ...

- Stripped out irrelevant tests.

Ensured that maximum and minimum column length assertions are only asserted where actually relevant.

Rewrote provideColumnLengths() to return fixed rather than variable-length result.

- Switched to new (il)legal value tests.

- Improved descriptive output. ...

- Added sqlifyValue function to improve flexibility of SQL string handling.
- Renamed 'type' property to 'sql_type'.
- Added 'generic_type' property.
- Improved testing of legal and illegal values.

- Split Order_line testing into "structure" and "data" tests. ...

- Modified Phone attribute test values (Staff, Supplier).
- Changed lower bound on Qty_Ordered to 1.
- Added lower bound constraint to Qty_Received.

- Split Order_head testing into "structure" and "data" tests. ...

- Modified Phone attribute test values (Staff, Supplier).
- Modified Due_Date attribute to NOT NULL.

- Split Sale_line testing into "structure" and "data" tests. ...

- Modified Phone attribute test values (Staff, Customer).
- Reduced Quantity attribute length to 4.

Added preliminary output based on whether an illegal value is rejected by a constraint or an actual overflow.

- Split Sale_head testing into "structure" and "data" tests. ...

- Modified Phone attribute test values (Staff, Customer).

- Split Assembly testing into "structure" and "data" tests. ...

- Modified Phone attribute test values (Supplier).

- Split Component testing into "structure" and "data" tests. ...

- Modified Phone attribute test values (Supplier).

Split Product testing into structure and data tests.

- Split Supplier testing into "structure" and "data" tests. ...

- Modified Phone attribute test values.

- Split Customer testing into "structure" and "data" tests. ...

- Modified Phone attribute test values.

Split Staff testing into separate "structure" and "data" tests.

- Slightly tidier printing of messages involving plurals. ...

- Now properly handles both "check constraint violated" and "value larger than specified precision" errors.

Added empty data fixture for structure-only testing.

Added experimental unit testing code.