suite.Run: simplify running of Setup/TeardownSuite (#1769)

## Summary
Improve readability of suite.Run by moving the running of SetupSuite
outside of the loop iterating over the (test) methods.
This also allows for other simplifications further down in the code.

## Changes
- Move SetupSuite to outside the loop
- Don't run Setup/TeardownSuite if no tests are found (not new
behaviour, but new check)
- Remove variable to keep track of wether SetupSuite was executed or not

## Motivation
This is a subset of the changes I made under PR #1749. It was suggested
by @dolmen to open a separate PR for this part.

## Related issues
N/A

Author: renzoarreaza

suite/suite.go

@@ -128,8 +128,6 @@ func Run(t *testing.T, suite TestingSuite) {
 	suite.SetT(t)
 	suite.SetS(suite)
 
-	var suiteSetupDone bool
-
 	var stats *SuiteInformation
 	if _, ok := suite.(WithStats); ok {
 		stats = newSuiteInformation()
@@ -152,18 +150,6 @@ func Run(t *testing.T, suite TestingSuite) {
 			continue
 		}
 
-		if !suiteSetupDone {
-			if stats != nil {
-				stats.Start = time.Now()
-			}
-
-			if setupAllSuite, ok := suite.(SetupAllSuite); ok {
-				setupAllSuite.SetupSuite()
-			}
-
-			suiteSetupDone = true
-		}
-
 		test := test{
 			name: method.Name,
 			run: func(t *testing.T) {
@@ -208,19 +194,30 @@ func Run(t *testing.T, suite TestingSuite) {
 		}
 		tests = append(tests, test)
 	}
-	if suiteSetupDone {
-		defer func() {
-			if tearDownAllSuite, ok := suite.(TearDownAllSuite); ok {
-				tearDownAllSuite.TearDownSuite()
-			}
-
-			if suiteWithStats, measureStats := suite.(WithStats); measureStats {
-				stats.End = time.Now()
-				suiteWithStats.HandleStats(suiteName, stats)
-			}
-		}()
+
+	if len(tests) == 0 {
+		return
+	}
+
+	if stats != nil {
+		stats.Start = time.Now()
+	}
+
+	if setupAllSuite, ok := suite.(SetupAllSuite); ok {
+		setupAllSuite.SetupSuite()
 	}
 
+	defer func() {
+		if tearDownAllSuite, ok := suite.(TearDownAllSuite); ok {
+			tearDownAllSuite.TearDownSuite()
+		}
+
+		if suiteWithStats, measureStats := suite.(WithStats); measureStats {
+			stats.End = time.Now()
+			suiteWithStats.HandleStats(suiteName, stats)
+		}
+	}()
+
 	runTests(t, tests)
 }