ruby - Difference between or and || when setting variables

Question

I was under the impression that || and or were synonymous.

Setting variable with or does not hold value; why?

>> test = nil or true
=> true
>> test
=> nil

>> test = false or true
=> true
>> test
=> false

Works 'as expected' with ||

>> test = nil || true
=> true
>> test
=> true

Answer 1

or has lower precedence than =.

test = nil or true

is the same as

(test = nil) or true

which is true, while setting test to nil.

|| has higher precedence than =.

test = nil || true

is the same as

test = (nil || true)

which is true, while setting test to true.