Prototype version with 2 level downsampling, supporting single channel data

[yftzz]

1. lttb, max, min, avg downsample strategies supported
2. 2 level preprocessing, first happening before the first request, second happens at each HTTP request
3. Users can switch downsample strategy without zoom-out, so that they can compare the results from each strategy.

[yftzz]

https://github.com/googleinterns/power-data-graphing-intern-2020/blob/5f74ac3a505289212e34065f63e7d4388880363d/frontend/src/app/app.component.spec.ts#L33-L37 In this test, I find the compiler warning that Property 'title' does not exist on type 'AppComponent'.ts(2339). The original app.component.ts looks like https://github.com/googleinterns/power-data-graphing-intern-2020/blob/4bd6c1f3be752ef3167ddf318b1214a1d9d3e8b7/frontend/src/app/app.component.ts#L1-L26 which does not have a title member as well. I'm wondering if this a typo or am I missing something? @Longzhao-Google

[Longzhao-Google]

https://github.com/googleinterns/power-data-graphing-intern-2020/blob/5f74ac3a505289212e34065f63e7d4388880363d/frontend/src/app/app.component.spec.ts#L33-L37

In this test, I find the compiler warning that Property 'title' does not exist on type 'AppComponent'.ts(2339). The original app.component.ts looks like https://github.com/googleinterns/power-data-graphing-intern-2020/blob/4bd6c1f3be752ef3167ddf318b1214a1d9d3e8b7/frontend/src/app/app.component.ts#L1-L26

which does not have a title member as well. I'm wondering if this a typo or am I missing something? @Longzhao-Google

So in your test, you are creating the component by running "const app = fixture.componentInstance", just imagine it works the same as const app = new AppComponent(); Now you have the reference of the component, you are trying to get the title variable of the component by running "app.title", but in your AppComponent class, there is no variable named as 'title', which causes the error. Is this test auto generated by the compiler? if so, you can delete it or modify it to fit your current code.

[yaomeng-google]

Just found the python unit test framework - pytest is already included in python3. So you should be able to write python tests without any issues. I tried to add a python test locally - test_example.py and run it with "pytest" command which works. Following are the content of the test_example.py and the pytest output. Please feel free to add your python tests in the coming commits. Technically, each python method should have at least 1 test method. For example, create a main_test.py which includes all the tests for each method in main.py.

(venv) yaomeng@yaomeng:~/github/power-data-graphing-intern-2020/backend$ cat test_example.py `

class TestExampleClass:

def test_should_pass(self):
    x = "this"
    assert "h" in x

def test_should_fail(self):
    x = "hello"
    assert hasattr(x, "check")

`

`

$ pytest ========================= test session starts ========================= platform linux -- Python 3.7.7, pytest-5.4.3, py-1.8.1, pluggy-0.13.1 rootdir: /usr/local/google/home/yaomeng/github/power-data-graphing-intern-2020/backend plugins: localserver-0.5.0, cov-2.10.0 collected 2 items

test_example.py .F [100%]

============================== FAILURES =============================== __ TestExampleClass.test_should_fail __

self = <test_example.TestExampleClass object at 0x7f99b7c35990> def test_should_fail(self): x = "hello" > assert hasattr(x, "check") E AssertionError: assert False E + where False = hasattr('hello', 'check') test_example.py:8: AssertionError ======================= short test summary info ======================= FAILED test_example.py::TestExampleClass::test_should_fail - Asserti... ===================== 1 failed, 1 passed in 0.07s =====================

`

[yftzz]

Just added unit tests for backend functions, including downsample strategies and utils functions.