Channels/api4 testing improvements (#22938)

* api4/post_test: fix missing TearDown

* api4/plugin_test: dont test timeout, saving 120s

* api4/channel_test: dont try to delete town square

* api4/channel_test: check public channel names deterministically

* api4/file_test: fix darwin assertions on go files

* api4/notify_admin_test: fix expect/actual order

* api4/team_test: make TestGetAllTeams deterministic

* api4/plugin_test: avoid nested test helpers

* api4/post_test: avoid nested test helpers

* api4/websocket_test: externalize log buffer

* testlib/helper: unset common env

* linting issues

* simplify TestGetFileHeaders

* team_test: leverage ElementsMatch

server/channels/api4/notify_admin_test.go

@@ -22,7 +22,7 @@ func TestNotifyAdmin(t *testing.T) {
 		})
 
 		require.Error(t, err)
-		require.Equal(t, err.Error(), ": Unable to save notify data.")
+		require.Equal(t, ": Unable to save notify data.", err.Error())
 		require.Equal(t, http.StatusInternalServerError, statusCode)
 
 	})
@@ -38,7 +38,7 @@ func TestNotifyAdmin(t *testing.T) {
 		})
 
 		require.Error(t, err)
-		require.Equal(t, err.Error(), ": Unable to save notify data.")
+		require.Equal(t, ": Unable to save notify data.", err.Error())
 		require.Equal(t, http.StatusInternalServerError, statusCode)
 
 	})
@@ -53,7 +53,7 @@ func TestNotifyAdmin(t *testing.T) {
 		})
 
 		require.Error(t, err)
-		require.Equal(t, err.Error(), ": Unable to save notify data.")
+		require.Equal(t, ": Unable to save notify data.", err.Error())
 		require.Equal(t, http.StatusInternalServerError, statusCode)
 	})
 
@@ -68,7 +68,7 @@ func TestNotifyAdmin(t *testing.T) {
 		})
 
 		require.Error(t, err)
-		require.Equal(t, err.Error(), ": Unable to save notify data.")
+		require.Equal(t, ": Unable to save notify data.", err.Error())
 		require.Equal(t, http.StatusInternalServerError, statusCode)
 	})
 
@@ -90,7 +90,7 @@ func TestNotifyAdmin(t *testing.T) {
 		})
 		require.Error(t, err)
 
-		require.Equal(t, err.Error(), ": Already notified admin")
+		require.Equal(t, ": Already notified admin", err.Error())
 		require.Equal(t, http.StatusForbidden, statusCode)
 	})
 
@@ -118,7 +118,7 @@ func TestTriggerNotifyAdmin(t *testing.T) {
 		statusCode, err := th.SystemAdminClient.TriggerNotifyAdmin(&model.NotifyAdminToUpgradeRequest{})
 
 		require.Error(t, err)
-		require.Equal(t, err.Error(), ": Internal error during cloud api request.")
+		require.Equal(t, ": Internal error during cloud api request.", err.Error())
 		require.Equal(t, http.StatusForbidden, statusCode)
 
 	})
@@ -132,7 +132,7 @@ func TestTriggerNotifyAdmin(t *testing.T) {
 		statusCode, err := th.Client.TriggerNotifyAdmin(&model.NotifyAdminToUpgradeRequest{})
 
 		require.Error(t, err)
-		require.Equal(t, err.Error(), ": You do not have the appropriate permissions.")
+		require.Equal(t, ": You do not have the appropriate permissions.", err.Error())
 		require.Equal(t, http.StatusForbidden, statusCode)
 	})