Improve performance from O(n2) to O(n) (#2)

* First commit of new version

* Improve error handling also remove unnecessary tests

* Improve error handling also remove unnecessary tests

* Fix total number of statements

* Make ParseTotalStatements a method of CoverProfile instead of normal function

* Sum the total statements in the ParseCoverProfile function

* Uses ok instead exists to follow Go community common pratices

* Simplify code using os.ReadDir instead of filepath.Walk since there is no subdirectories

* Improves outputs

* Unexport function already called in the object instantiation (newCoverProfile)

* Rename testdata directory

* New line should be added by print

* Fix bug on output for many functions

* Generate cover profiles

* Remove useless check

* Got everything working

* Update gitignore

* Refactored

* Improve test to check stringer interface

* Delete code commented out

* Add table tests for two biggest behaviours

* Add simplecode testdata directory

* Add integration tests using testscript

* Move specific test of String() method to testscript

* Nothing else on my code uses dash

* Update the readme

.gitignore

@@ -13,3 +13,5 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+
+*.coverprofile

README.md

@@ -12,24 +12,38 @@ go install github.com/broadwing/deltacoverage/cmd/deltacoverage@latest
 
 ```shell
 $ deltacoverage
-TestParseCoverageResult_ErrorsIfGivenNoTests 1.0%
-TestParseCoverageResult_ReturnsCorrectValueGivenTestScriptTestCoverResult 3.2%
-TestParseCoverageResult_ReturnsCorrectValueGivenNoTestScriptsTestCoverResult 0.0%
-TestParseListTests_ReturnsZeroTestsIfGivenNoTests 0.0%
-TestParseListTests_ReturnsCorrectValuesGivenTestListResult 0.0%
-TestTestScript_ 54.2%
+TestCleanup_RemovesOutputPath 0.7%
+TestGenerate_CreatesExpectedCoverProfilesGivenCode 7.2%
+TestGenerate_ErrorsGivenCodeWithNoTests 1.4%
+TestListTests_SetsExpectedTestsNamesGivenCode 0.0%
+TestNewCoverProfile_ErrorsIfPathDoesNotExist 0.7%
+TestNewCoverProfile_ErrorsIfPathIsNotDirectory 0.7%
+TestNewCoverProfile_SetsCorrectPackagePathGivenString 0.0%
+TestNewCoverProfile_SetsNonEmptyOutputPath 0.0%
+TestParse_ReturnsExpectedNumberStatementsGivenOutputPath 0.0%
+TestParse_ReturnsExpectedTestsBranchesGivenOutputPath 0.0%
+TestParse_ReturnsExpectedUniqueBranchesGivenOutputPath 0.0%
+TestString_ReturnsExpectedDeltaCoverageGivenCoverProfile 10.1%
 ```
 
-The test `TestParseCoverageResult_ErrorsIfGivenNoTests` contributes to exclusive
-1.0% of the total coverage while `TestScript_` is responsible for 54.2%.
+The test `TestCleanup_RemovesOutputPath` contributes to exclusive
+0.7% of the total coverage while
+`TestString_ReturnsExpectedDeltaCoverageGivenCoverProfile` is responsible for
+10.1%.
+
+Although the tests `TestNewCoverProfile_SetsCorrectPackagePathGivenString` and
+`TestNewCoverProfile_SetsNonEmptyOutputPath` have no delta coverage or 0.0%, it is okay
+since we are testing behaviours and not functions. The tests run the same code
+path but test different things. Also, this design allow ease understand
+of what is the test supposed to do.
 
 ## Motivation
 
 ```text
-Herb Derby came up with this metric of “delta coverage”. 
+Herb Derby came up with this metric of “delta coverage”.
 You look at your test suite and you measure what coverage each test adds uniquely that no other test provides.
-If you have lots of tests with no delta coverage, so that you could just delete them and not lose your 
-ability to exercise parts of the system, then you should delete those tests, unless they have some some 
+If you have lots of tests with no delta coverage, so that you could just delete them and not lose your
+ability to exercise parts of the system, then you should delete those tests, unless they have some some
 communication purpose.
 —Kent Beck, “Is TDD Dead?”
 ```
@@ -40,6 +54,6 @@ Thank you [@bitfield](https://github.com/bitfield) for the suggestion.
 
 - POC :white_check_mark:
 - Brute force implementation using `go test` commands :white_check_mark:
-- Get same metrics using coverprofiles of each test instead of brute force. It's going to improve performance from O(n2) to O(n) -> WIP
-- Borrow `cover.go` code and create `deltagecoverage.go`
+- Get same metrics using coverprofiles of each test instead of brute force. It's going to improve performance from O(n2) to O(n):white_check_mark:
+- Borrow `cover.go` code and create `deltagecoverage.go` -> Under analysis
 - (Dream) Implement as Go CLI feature