diff --git a/src/test/kotlin/kestrel/CheckConstraintTest.kt b/src/test/kotlin/kestrel/CheckConstraintTest.kt
new file mode 100644
index 0000000..2198e92
--- /dev/null
+++ b/src/test/kotlin/kestrel/CheckConstraintTest.kt
@@ -0,0 +1,111 @@
+package kestrel
+
+import kestrel.catalog.Catalog
+import kestrel.engine.Executor
+import kestrel.engine.InsertResult
+import kestrel.engine.SelectResult
+import kestrel.engine.StatementResult
+import kestrel.engine.UpdateResult
+import kestrel.sql.lexer.Lexer
+import kestrel.sql.parser.Parser
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+import kotlin.test.assertTrue
+
+class CheckConstraintTest {
+    private val catalog = Catalog()
+    private val executor = Executor(catalog)
+
+    private fun run(sql: String): List<StatementResult> =
+        Parser(Lexer(sql).tokenize()).parseProgram().map { executor.execute(it) }
+
+    private fun exec(sql: String): StatementResult = run(sql).single()
+
+    private fun select(sql: String): SelectResult = exec(sql) as SelectResult
+
+    @Test
+    fun columnLevelCheckAcceptsSatisfyingRows() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY, age INTEGER CHECK (age > 0))")
+        assertEquals(InsertResult(1), exec("INSERT INTO t VALUES (1, 30)"))
+    }
+
+    @Test
+    fun columnLevelCheckRejectsViolatingRows() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY, age INTEGER CHECK (age > 0))")
+        val error = assertFailsWith<KestrelException> { run("INSERT INTO t VALUES (1, -5)") }
+        assertTrue(error.message!!.contains("CHECK"))
+    }
+
+    @Test
+    fun checkPassesWhenExpressionIsUnknownBecauseOfNull() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY, age INTEGER CHECK (age > 0))")
+        // three-valued logic: NULL > 0 is UNKNOWN, not FALSE, so the row is accepted
+        assertEquals(InsertResult(1), exec("INSERT INTO t VALUES (1, NULL)"))
+    }
+
+    @Test
+    fun tableLevelCheckCanSpanMultipleColumns() {
+        run("CREATE TABLE ranges (id INTEGER PRIMARY KEY, low INTEGER, high INTEGER, CHECK (low <= high))")
+        assertEquals(InsertResult(1), exec("INSERT INTO ranges VALUES (1, 1, 10)"))
+        assertFailsWith<KestrelException> { run("INSERT INTO ranges VALUES (2, 10, 1)") }
+    }
+
+    @Test
+    fun multipleCheckConstraintsAllMustBeSatisfied() {
+        run(
+            "CREATE TABLE t (id INTEGER PRIMARY KEY, age INTEGER CHECK (age >= 0), " +
+                "score INTEGER CHECK (score BETWEEN 0 AND 100))"
+        )
+        assertEquals(InsertResult(1), exec("INSERT INTO t VALUES (1, 30, 90)"))
+        assertFailsWith<KestrelException> { run("INSERT INTO t VALUES (2, 30, 150)") }
+        assertFailsWith<KestrelException> { run("INSERT INTO t VALUES (3, -1, 90)") }
+    }
+
+    @Test
+    fun checkIsEnforcedOnUpdateToo() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY, age INTEGER CHECK (age > 0))")
+        run("INSERT INTO t VALUES (1, 30)")
+        assertFailsWith<KestrelException> { run("UPDATE t SET age = -1 WHERE id = 1") }
+        assertEquals(UpdateResult(1), exec("UPDATE t SET age = 40 WHERE id = 1"))
+    }
+
+    @Test
+    fun checkRejectsAggregateFunctions() {
+        assertFailsWith<KestrelException> {
+            run("CREATE TABLE t (id INTEGER PRIMARY KEY, amount INTEGER CHECK (SUM(amount) > 0))")
+        }
+    }
+
+    @Test
+    fun checkRejectsSubqueries() {
+        run("CREATE TABLE other (id INTEGER PRIMARY KEY)")
+        assertFailsWith<KestrelException> {
+            run("CREATE TABLE t (id INTEGER PRIMARY KEY CHECK (id IN (SELECT id FROM other)))")
+        }
+    }
+
+    @Test
+    fun checkRejectsUnknownColumn() {
+        assertFailsWith<KestrelException> {
+            run("CREATE TABLE t (id INTEGER PRIMARY KEY, CHECK (nope > 0))")
+        }
+    }
+
+    @Test
+    fun checkCanReferenceStringAndCallExpressions() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY, name TEXT CHECK (LENGTH(name) > 0))")
+        assertEquals(InsertResult(1), exec("INSERT INTO t VALUES (1, 'ada')"))
+        assertFailsWith<KestrelException> { run("INSERT INTO t VALUES (2, '')") }
+    }
+
+    @Test
+    fun checkConstraintSurvivesRollback() {
+        run("CREATE TABLE t (id INTEGER PRIMARY KEY, age INTEGER CHECK (age > 0))")
+        run("BEGIN")
+        run("INSERT INTO t VALUES (1, 30)")
+        run("ROLLBACK")
+        assertFailsWith<KestrelException> { run("INSERT INTO t VALUES (1, -5)") }
+        assertEquals(0, select("SELECT * FROM t").rows.size)
+    }
+}