start_test: Add fallback when shell cannot be detected

Running `make check` as part of `rpmbuild` inside a container causes
shell.GetShell("") to fail, and thus `start_test` fails as well.
This commit adds an OS  dependant fallback when the shell cannot be
detected while running the test case.

Author: cfergeau

cmd/crc/cmd/start_test.go

@@ -34,7 +34,15 @@ func TestRenderActionPlainSuccess(t *testing.T) {
 		},
 	}, out, ""))
 
+	var userShell string
 	userShell, err := shell.GetShell("")
+	if err != nil {
+		if runtime.GOOS == "windows" {
+			userShell, err = shell.GetShell("cmd")
+		} else {
+			userShell, err = shell.GetShell("bash")
+		}
+	}
 	assert.NoError(t, err)
 	assert.Equal(t, expectedTemplate(userShell), out.String())
 }