Replace gopkg.in/check.v1 by github.com/stretchr/testify/suite/

gopkg.in/check.v1 hasn't had any commit since Nov 2020.
That's not a immediate issue for a test-only dependency, but
because it hides access to the standard library *testing.T,
eventually it will become limiting.

Also, using the same framework for unit and integration tests
seems practical.

This is mostly a batch copy&paste job, with a fairly high risk
of unexpected breakage.

Also, I didn't take much time at all to carefully choose between
assert.* and require.*; we can tune that as failures show up.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

vendor/github.com/stretchr/testify/suite/stats.go

@@ -0,0 +1,46 @@
+package suite
+
+import "time"
+
+// SuiteInformation stats stores stats for the whole suite execution.
+type SuiteInformation struct {
+	Start, End time.Time
+	TestStats  map[string]*TestInformation
+}
+
+// TestInformation stores information about the execution of each test.
+type TestInformation struct {
+	TestName   string
+	Start, End time.Time
+	Passed     bool
+}
+
+func newSuiteInformation() *SuiteInformation {
+	testStats := make(map[string]*TestInformation)
+
+	return &SuiteInformation{
+		TestStats: testStats,
+	}
+}
+
+func (s SuiteInformation) start(testName string) {
+	s.TestStats[testName] = &TestInformation{
+		TestName: testName,
+		Start:    time.Now(),
+	}
+}
+
+func (s SuiteInformation) end(testName string, passed bool) {
+	s.TestStats[testName].End = time.Now()
+	s.TestStats[testName].Passed = passed
+}
+
+func (s SuiteInformation) Passed() bool {
+	for _, stats := range s.TestStats {
+		if !stats.Passed {
+			return false
+		}
+	}
+
+	return true
+}