add class methods, unit tests for flytefile and flytedirectory

[granthamtaylor]

I feel like it is verbose to get the working directory (flytekit.current_context().working_directory) in a task. I find myself doing this very, very frequently, primarily to write files. I use the working directory so that files won’t get written to my local working directory during local execution.

I had thought about this for a while, and the more I thought about what exactly I wanted to accomplish, I feel like it should be accomplished with a few new classmethod for FlyteFile / FlyteDirectory...

---

This task...

@task
def my_task() -> FlyteFile:
    local_path = os.path.join(current_context().working_directory, "data.txt")
    with open(local_path, mode="w") as file:
        file.write("Here is some sample data.")
    return FlyteFile(path=local_path)

Should ideally be replaced with something like this:

@task
def my_task() -> FlyteFile:

    ff = FlyteFile.new('myfile.txt')

    with open(ff, mode="w") as file:
        file.write("Here is some sample data.")

    return ff

In this case, FlyteFile.new will create a FlyteFile with a path of the filename inside of the working directory (current_context().working_directory).

---

The same goes for FlyteDirectory...

@task
def my_task() -> FlyteDirectory:

    p = os.path.join(current_context().working_directory, "my_new_directory")

    os.makedirs(p)

    with open(os.path.join(p, "file_1.txt"), 'w') as file:
        file.write("This is file 1.")

    return FlyteDirectory(p)

Should be replaced with:

@task
def my_task() -> FlyteDirectory:

    dir = FlyteDirectory.new('my_new_directory')

    with open(dir / "file_1.txt", 'w') as file:
        file.write("This is file 1.")

    return dir

In this case, FlyteDirectory.new will create the directory my_new_directory under current_context().working_directory, and ensure that it exists (os.makedirs(dir.path))

Additionally, I am overloading the __truedivide__ operator to FlyteDirectory for convenience:

class FlyteDirectory:

    ...

    def __truedivide__(self, other: str | os.PathLike) -> Path:
        """
        This is a convenience method to allow for easy concatenation of paths.
        """
        return Path(self.path) / other

[codecov]

Codecov Report

Attention: Patch coverage is 76.47059% with 4 lines in your changes missing coverage. Please review.

Project coverage is 73.03%. Comparing base (3fc51af) to head (ba9b4b8).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
flytekit/types/directory/types.py	80.00%	1 Missing and 1 partial ⚠️
flytekit/types/file/file.py	71.42%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #2852       +/-   ##
===========================================
+ Coverage   45.53%   73.03%   +27.50%     
===========================================
  Files         196      196               
  Lines       20418    20471       +53     
  Branches     2647     2650        +3     
===========================================
+ Hits         9298    14952     +5654     
+ Misses      10658     4798     -5860     
- Partials      462      721      +259     

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[eapolinario]

I love the exist_ok=False.