Prefer string.Contains() over string.IndexOf() != -1

[terrajobst]

Calls to String.IndexOf(...) where the result is then just compared to -1 can instead be replaced by calls to String.Contains(...).

Category: Performance

[jeffhandley]

Estimates:

• Analyzer: Small
• Fixer: Small

[stephentoub]

We actually need to be a bit careful on this one. For whatever reason, the semantics of string.IndexOf vs string.Contains differ, in that the former does a culture-aware comparison and the latter does an ordinal comparison.

[terrajobst]

We discussed this today and concluded we should offer two fixers:

• Replace with String.Contains and use ordinal
• Replace with String.Contains and preserve culture sensitive comparison

(wording to be defined)