Fix flaky test TestCommitStatusTargetURL (#39)

The test added in [1] uses environment variables in a parallel test
which causes it to be flaky and sometimes fail as is described in [2].

To fix the flaky test, the environment variable is pulled out and read
in the caller of the function under test, so that it can be tested
without reading the global environment variable.

[1] a43d3d1
[2] https://pkg.go.dev/testing#T.Setenv

internal/pkg/githubapi/github.go

@@ -854,7 +854,9 @@ func SetCommitStatus(ghPrClientDetails GhPrClientDetails, state string) {
 	tcontext := "telefonistka"
 	avatarURL := "https://avatars.githubusercontent.com/u/1616153?s=64"
 	description := "Telefonistka GitOps Bot"
-	targetURL := commitStatusTargetURL(time.Now())
+	tmplFile := os.Getenv("CUSTOM_COMMIT_STATUS_URL_TEMPLATE_PATH")
+
+	targetURL := commitStatusTargetURL(time.Now(), tmplFile)
 
 	commitStatus := &github.RepoStatus{
 		TargetURL:   &targetURL,
@@ -1273,10 +1275,9 @@ func GetFileContent(ghPrClientDetails GhPrClientDetails, branch string, filePath
 // If the template file is not found or an error occurs during template execution,
 // it returns a default URL.
 // passed parameter commitTime can be used in the template as .CommitTime
-func commitStatusTargetURL(commitTime time.Time) string {
+func commitStatusTargetURL(commitTime time.Time, tmplFile string) string {
 	const targetURL string = "https://github.com/wayfair-incubator/telefonistka"
 
-	tmplFile := os.Getenv("CUSTOM_COMMIT_STATUS_URL_TEMPLATE_PATH")
 	tmplName := filepath.Base(tmplFile)
 
 	// dynamic parameters to be used in the template

internal/pkg/githubapi/github_test.go

@@ -395,15 +395,12 @@ func TestCommitStatusTargetURL(t *testing.T) {
 
 			expectedURL := tc.expectedURL
 			if tc.templateFile != "" {
-				os.Setenv("CUSTOM_COMMIT_STATUS_URL_TEMPLATE_PATH", tc.templateFile)
-				defer os.Unsetenv("CUSTOM_COMMIT_STATUS_URL_TEMPLATE_PATH")
-
 				if tc.validTemplate {
 					expectedURL = fmt.Sprintf(expectedURL, now.UnixMilli(), now.Add(-10*time.Minute).UnixMilli())
 				}
 			}
 
-			result := commitStatusTargetURL(now)
+			result := commitStatusTargetURL(now, tc.templateFile)
 			if result != expectedURL {
 				t.Errorf("%s: Expected URL to be %q, got %q", name, expectedURL, result)
 			}