test and fix signal_camera upgrade problems

- after 3->4 upgrade, it left the foreign key referring to the
  nonexistent old_camera table. Likely no one who did the upgrade
  has ever inserted anything into this table, so no one's noticed.
- 6->7 upgrade dropped tables in the wrong order, so if there was
  anything in the signal_camera table, the upgrade would fail.

server/db/upgrade/mod.rs

@@ -296,8 +296,25 @@ mod tests {
                 // anything left over.
                 assert!(!garbage.exists());
                 std::fs::File::create(&garbage)?;
-            }
+            } else if *ver == 4 {
-            if *ver == 6 {
+                // First version that supports signals. Add them and ensure they don't break
+                // subsequent upgrades.
+                upgraded.execute_batch(
+                    r#"
+                    insert into signal (id, source_uuid, type_uuid, short_name)
+                                values (1, x'1B3889C0A59F400DA24C94EBEB19CC3A',
+                                        x'EE66270FD9C648198B339720D4CBCA6B', 'a'),
+                                       (2, x'A4A73D9A53424EBCB9F6366F1E5617FA',
+                                        x'EE66270FD9C648198B339720D4CBCA6B', 'b');
+                    insert into signal_type_enum (type_uuid, value, name, motion, color)
+                       values (x'EE66270FD9C648198B339720D4CBCA6B', 1, 'still', 0, 'black'),
+                              (x'EE66270FD9C648198B339720D4CBCA6B', 2, 'moving', 1, 'red');
+                    insert into signal_camera (signal_id, camera_id, type)
+                                       values (1, 1, 0),
+                                              (2, 1, 1);
+                "#,
+                )?;
+            } else if *ver == 6 {
                 // Check that the pasp was set properly.
                 let mut stmt = upgraded.prepare(
                     r#"

server/db/upgrade/v3_to_v4.rs

@@ -27,13 +27,6 @@ pub fn run(_args: &super::Args, tx: &rusqlite::Transaction) -> Result<(), Error>
           color text
         );
 
-        create table signal_camera (
-          signal_id integer references signal (id),
-          camera_id integer references camera (id),
-          type integer not null,
-          primary key (signal_id, camera_id)
-        ) without rowid;
-
         create table signal_change (
           time_90k integer primary key,
           changes blob not null
@@ -69,6 +62,13 @@ pub fn run(_args: &super::Args, tx: &rusqlite::Transaction) -> Result<(), Error>
         from
           old_camera;
 
+        create table signal_camera (
+          signal_id integer references signal (id),
+          camera_id integer references camera (id),
+          type integer not null,
+          primary key (signal_id, camera_id)
+        ) without rowid;
+
         alter table stream rename to old_stream;
         create table stream (
           id integer primary key,

server/db/upgrade/v6_to_v7.rs

@@ -457,10 +457,9 @@ pub fn run(_args: &super::Args, tx: &rusqlite::Transaction) -> Result<(), Error>
           composite_id integer not null,
           primary key (sample_file_dir_id, composite_id)
         ) without rowid;
-        drop index recording_cover;
         insert into garbage select * from old_garbage;
         drop table old_garbage;
-
+        drop index recording_cover;
         alter table recording rename to old_recording;
         create table recording (
           composite_id integer primary key,
@@ -510,8 +509,8 @@ pub fn run(_args: &super::Args, tx: &rusqlite::Transaction) -> Result<(), Error>
           video_index blob not null check (length(video_index) > 0)
         );
         insert into recording_playback select * from old_recording_playback;
-        drop table old_signal;
         drop table signal_camera;
+        drop table old_signal;
         drop table old_recording_playback;
         drop table old_recording_integrity;
         drop table old_recording;