testutil: add Session

[System-Glitch]

References

Issue(s): closes #233

Description

testutil.Session is a new testing utility used to mock the session.Session interface. This implementation is designed to provide a realistic, observable transaction system and help identify incorrect usage. You can find more details in the godoc on the testutil.Session struct.

Usage example:

session := testutil.NewTestSession()
service := NewService(repo, session)

createDTO := &dto.CreateUserRequest{
	//...
}
created, err := service.Create(context.Background(), createDTO)
require.NoError(t, err)
expected := &dto.User{
	//...
}
assert.Equal(t, expected, created)

txs := session.Children()
if assert.Len(t, txs, 1) {
	assert.Equal(t, testutil.SessionCommitted, txs[0].Status())
}

Possible drawbacks

• The incorrect session usage detection is quite strict and may force developers to write their services in a certain way. On the other hand, this sounds good to me because code that doesn't meet these criteria would be flawed anyway and wouldn't be reliable. Please feel free to add some feedback regarding this.

[coveralls]

Pull Request Test Coverage Report for Build 12034777957

Details

• 88 of 90 (97.78%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.005%) to 97.475%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
util/testutil/session.go	88	90	97.78%

Totals
Change from base Build 12014896572:	0.005%
Covered Lines:	6407
Relevant Lines:	6573

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💛 - Coveralls