Pattern: Missing use of single quotes
Issue: -
DO use single quotes where they wouldn't require additional escapes.
That means strings with an apostrophe may use double quotes so that the apostrophe isn't escaped (note: we don't lint the other way around, ie, a single quoted string with an escaped apostrophe is not flagged).
It's also rare, but possible, to have strings within string interpolations. In this case, its much more readable to use a double quote somewhere. So double quotes are allowed either within, or containing, an interpolated string literal. Arguably strings within string interpolations should be its own type of lint.
Example of incorrect code:
useStrings(
"should be single quote",
r"should be single quote",
r"""should be single quotes""")Example of correct code:
useStrings(
'should be single quote',
r'should be single quote',
r\'''should be single quotes\''',
"here's ok",
"nested \${a ? 'strings' : 'can'} be wrapped by a double quote",
'and nested \${a ? "strings" : "can be double quoted themselves"}');