Fix #414: Add StringToFractionParserTest

[viktoriias]

Explanation

Fixes #414: Add unit tests for StringToFractionParser.

Checklist

• The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
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[viktoriias]

@rt4914 Please review. Some imports have moved to the new packages, I updated the imports here.

[rt4914]

I have checked tests for this file and other app layer tests for robolectric and espresso and all tests are passing. I suppose the only solution is to merge this and check if this creates test failure once again or not.

[rt4914]

LGTM

[rt4914]

Again checked all tests on latest develop and they are passing correctly which was not the case earlier.

[rt4914]

Created #3215 to test on CI

[rt4914]

Confirmed in #3215 tests are now passing on CI too. Thanks @viktoriias