NewDateTime returns a unix 0, but IsZero checks for zero time.Time

[prashantv]

Repro:

dt := strfmt.NewDateTime()
fmt.Println("iszero", dt.IsZero())

Output:

iszero false

Want:

iszero true

The NewDateTime documentation says:

NewDateTime is a representation of zero value for DateTime type

and IsZero says:

IsZero returns whether the date time is a zero value

Given these docs, I expected that NewDateTime() would match the zero value (e.g., var d DateTime), and that IsZero() would be true for it. However, that's not the case as NewDateTime() returns Unix(0, 0) which is different from a zero DateTime.

A couple of approaches to fix this:

Approach 1: return time.Time{} in NewDateTime
Rather than initializing using time.Unix(0, 0), NewDateTime could return time.Time{}, which would better align with the docs, as it suggests that NewDateTime() should match var d strfmt.DateTime which it doesn't currently.

However, this likely has a larger impact for users of NewDateTime since the value returned is changing.

IMO this is the more correct fix.

Approach 2: Update IsZero
IsZero could be updated to check for IsUnixZero() in addition to checking for zero time.Time.

I would also recommend the documentation for NewDateTime is updated to indicate that it uses Unix(0, 0) rather than matching a zero DateTime.

[fredbi]

@prashantv I am proposing a PR which adds a new method to initialize with the "true" zero value and fixes the documentation of NewDateTime.