diff --git a/src/test/kotlin/kestrel/MergeTest.kt b/src/test/kotlin/kestrel/MergeTest.kt
index ce9f6e4..2112d87 100644
--- a/src/test/kotlin/kestrel/MergeTest.kt
+++ b/src/test/kotlin/kestrel/MergeTest.kt
@@ -310,3 +310,150 @@ class MergeTest {
         )
     }
 
+    @Test
+    fun rollingBackATransactionUndoesEveryEffectOfAMerge() {
+        setUpAccountsAndStaging()
+        run("INSERT INTO accounts VALUES (1, 100)")
+        run("INSERT INTO staging VALUES (1, 50), (2, 20)")
+        run("BEGIN")
+        exec(
+            "MERGE INTO accounts USING staging ON accounts.id = staging.id " +
+                "WHEN MATCHED THEN UPDATE SET balance = accounts.balance + staging.amount " +
+                "WHEN NOT MATCHED THEN INSERT (id, balance) VALUES (staging.id, staging.amount)"
+        )
+        run("ROLLBACK")
+        assertEquals(listOf(listOf(int(1), int(100))), select("SELECT id, balance FROM accounts").rows)
+    }
+
+    @Test
+    fun anAliasedTargetAndSourceCanBeReferencedByTheirAlias() {
+        setUpAccountsAndStaging()
+        run("INSERT INTO accounts VALUES (1, 100)")
+        run("INSERT INTO staging VALUES (1, 25)")
+        exec(
+            "MERGE INTO accounts AS acc USING staging AS s ON acc.id = s.id " +
+                "WHEN MATCHED THEN UPDATE SET balance = acc.balance + s.amount"
+        )
+        assertEquals(listOf(listOf(int(125))), select("SELECT balance FROM accounts").rows)
+    }
+
+    @Test
+    fun mergeRequiresAtLeastOneWhenClause() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY)")
+        run("CREATE TABLE s (id INTEGER)")
+        assertFailsWith<KestrelException> { run("MERGE INTO t USING s ON t.id = s.id") }
+    }
+
+    @Test
+    fun mergingIntoAnUnknownTableFails() {
+        run("CREATE TABLE s (id INTEGER)")
+        assertFailsWith<KestrelException> {
+            run("MERGE INTO nope USING s ON nope.id = s.id WHEN MATCHED THEN DELETE")
+        }
+    }
+
+    @Test
+    fun returningStarProjectsEveryColumnOfEveryActionedRow() {
+        setUpAccountsAndStaging()
+        run("INSERT INTO accounts VALUES (1, 100)")
+        run("INSERT INTO staging VALUES (1, 10), (2, 5)")
+        val result = exec(
+            "MERGE INTO accounts USING staging ON accounts.id = staging.id " +
+                "WHEN MATCHED THEN UPDATE SET balance = accounts.balance + staging.amount " +
+                "WHEN NOT MATCHED THEN INSERT (id, balance) VALUES (staging.id, staging.amount) " +
+                "RETURNING *"
+        ) as MergeResult
+        assertEquals(listOf("id", "balance"), result.returning!!.columns)
+        assertEquals(
+            listOf(listOf(int(1), int(110)), listOf(int(2), int(5))),
+            result.returning!!.rows
+        )
+    }
+
+    @Test
+    fun returningEvaluatesExpressionsAgainstTheAffectedRow() {
+        setUpAccountsAndStaging()
+        run("INSERT INTO accounts VALUES (1, 100)")
+        run("INSERT INTO staging VALUES (1, 10)")
+        val result = exec(
+            "MERGE INTO accounts USING staging ON accounts.id = staging.id " +
+                "WHEN MATCHED THEN UPDATE SET balance = accounts.balance + staging.amount " +
+                "RETURNING balance * 2 AS doubled"
+        ) as MergeResult
+        assertEquals(listOf("doubled"), result.returning!!.columns)
+        assertEquals(listOf(listOf(int(220))), result.returning!!.rows)
+    }
+
+    @Test
+    fun returningIncludesThePreDeletionImageOfADeletedRow() {
+        setUpAccountsAndStaging()
+        run("INSERT INTO accounts VALUES (1, 100)")
+        run("INSERT INTO staging VALUES (1, 0)")
+        val result = exec(
+            "MERGE INTO accounts USING staging ON accounts.id = staging.id WHEN MATCHED THEN DELETE RETURNING id, balance"
+        ) as MergeResult
+        assertEquals(listOf(listOf(int(1), int(100))), result.returning!!.rows)
+        assertEquals(emptyList(), select("SELECT * FROM accounts").rows)
+    }
+
+    @Test
+    fun mergeActionLabelsEachReturnedRowByWhichClauseFired() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY, label TEXT)")
+        run("CREATE TABLE s (id INTEGER, label TEXT)")
+        run("INSERT INTO t VALUES (1, 'old'), (2, 'gone')")
+        run("INSERT INTO s VALUES (1, 'new'), (2, 'new'), (3, 'fresh')")
+        val result = exec(
+            "MERGE INTO t USING s ON t.id = s.id " +
+                "WHEN MATCHED AND s.id = 2 THEN DELETE " +
+                "WHEN MATCHED THEN UPDATE SET label = s.label " +
+                "WHEN NOT MATCHED THEN INSERT (id, label) VALUES (s.id, s.label) " +
+                "RETURNING id, MERGE_ACTION() AS kind"
+        ) as MergeResult
+        assertEquals(
+            setOf(listOf(int(1), text("UPDATE")), listOf(int(2), text("DELETE")), listOf(int(3), text("INSERT"))),
+            result.returning!!.rows.toSet()
+        )
+    }
+
+    @Test
+    fun noRowMatchingAnyClauseReturnsAnEmptyReturningResultNotANullOne() {
+        setUpAccountsAndStaging()
+        run("INSERT INTO accounts VALUES (1, 100)")
+        run("INSERT INTO staging VALUES (1, 5)")
+        val result = exec(
+            "MERGE INTO accounts USING staging ON accounts.id = staging.id " +
+                "WHEN MATCHED AND staging.amount > 1000 THEN UPDATE SET balance = 0 " +
+                "RETURNING *"
+        ) as MergeResult
+        assertEquals(emptyList(), result.returning!!.rows)
+    }
+
+    @Test
+    fun mergeActionIsRejectedOutsideOfAMergesOwnReturningClause() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY)")
+        run("INSERT INTO t VALUES (1)")
+        val error = assertFailsWith<KestrelException> { select("SELECT MERGE_ACTION() FROM t") }
+        assertTrue(error.message!!.contains("MERGE_ACTION"), error.message)
+    }
+
+    @Test
+    fun mergeActionInAPlainInsertReturningIsRejectedOnceARowActuallyReturns() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY)")
+        val error = assertFailsWith<KestrelException> {
+            run("INSERT INTO t VALUES (1) RETURNING MERGE_ACTION()")
+        }
+        assertTrue(error.message!!.contains("MERGE_ACTION"), error.message)
+    }
+
+    @Test
+    fun returningColumnValidationRunsUpFrontEvenWhenNoSourceRowEverReachesAMatchingClause() {
+        setUpAccountsAndStaging()
+        val error = assertFailsWith<KestrelException> {
+            run(
+                "MERGE INTO accounts USING staging ON accounts.id = staging.id " +
+                    "WHEN MATCHED THEN DELETE RETURNING nope"
+            )
+        }
+        assertTrue(error.message!!.contains("no such column"), error.message)
+    }
+}