fixup! Break ties of PreferDistinct submissions with equal counts

Add doctest

Author: jerbaroo

justfile

@@ -41,7 +41,14 @@ clean:
 
 # Run all tests
 [group('test')]
-test: test-unit test-integration
+test: test-doc test-unit test-integration
+
+# Run doctests
+# Nextest doesn't currently support doctests
+# c.f. https://nexte.st/docs/integrations/test-coverage/
+[group('test')]
+test-doc *TEST_ARGS:
+  cargo test --doc --workspace {{TEST_ARGS}}
 
 # Rust unit test suite
 [group('test')]

opsqueue/src/consumer/strategy.rs

@@ -19,7 +19,7 @@ pub enum Strategy {
 }
 
 /// Iterator over the `meta_key`s of a chain of nested
-/// [`Strategy::PreferDistinct`]. outermost first. Stops at the first
+/// [`Strategy::PreferDistinct`], outermost first. Stops at the first
 /// non-`PreferDistinct` strategy, which can afterwards be retrieved with
 /// [`MetaKeysIter::take`].
 pub struct MetaKeysIter<'a> {
@@ -178,13 +178,25 @@ impl Strategy {
         }
     }
 
-    /// Append a query snippet to select from the `random_order` column on the
-    /// given table using the "cutting the deck" technique.
-    fn push_random_order_query<'a>(
+    /// Append a query snippet to a `QueryBuilder` to select `columns` using the
+    /// `random_order` column as a filter (the "cutting the deck" technique),
+    /// from table `table`.
+    ///
+    /// ```
+    /// use opsqueue::consumer::strategy::Strategy;
+    /// use sqlx::{QueryBuilder, Sqlite};
+    /// let mut qb: QueryBuilder<Sqlite> = QueryBuilder::new("");
+    /// Strategy::push_random_order_query(&mut qb, "id, name", "users", Some("status = 'active'"));
+    /// let expected_sql = "SELECT id, name FROM users WHERE random_order >= ? AND status = 'active' \
+    ///                     UNION ALL \
+    ///                     SELECT id, name FROM users WHERE random_order < ? AND status = 'active'";
+    /// assert_eq!(qb.sql(), expected_sql);
+    /// ```
+    pub fn push_random_order_query<'a>(
         qb: &'a mut QueryBuilder<Sqlite>,
-        columns: &str,
-        table_name: &str,
-        condition: Option<&str>,
+        columns: &'static str,
+        table_name: &'static str,
+        condition: Option<&'static str>,
     ) -> &'a mut QueryBuilder<Sqlite> {
         let random_offset: u16 = rand::random();
         let push_select = |qb: &mut QueryBuilder<Sqlite>, operator: &str| {