Context

• node version: v6.10.2
• joi version: v10.4.2
• environment (node, browser): node
• used with (hapi, standalone, ...): standalone
• any other relevant information: macOS 10.12.14

What are you trying to achieve or the steps to reproduce ?

I thought it was fairly confusing that these options do not work together

const schema = Joi.string().valid(['A', 'B', 'C']).insensitive().lowercase()
schema.validate('A')
// { error: null, value: 'A' }
// or for uppercase
const anotherSchema = Joi.string().valid(['a', 'b', 'c']).insensitive().uppercase()
anotherSchema.validate('b')
// { error: null, value: 'b' }

Which result you had ?

After validation with schema, the value was 'A'
After validation with anotherSchema, the value was 'b'

What did you expect ?

After validation with schema, the value should be 'a'
After validation with anotherSchema, the value should be 'B'

Now its fine that there is a workaround to just convert the array to the correct casing and use:

Joi.string().valid(['a', 'b', 'c']).lowercase();
schema.validate('A')
// { error: null, value: 'a' }

but seems like odd behavior for this to not work with both. I can submit a PR if you agree.

Thanks for Joi!