[Spec tests] Add contracts tests

compiler/tests-spec/testData/diagnostics/notLinked/contracts/analysis/smartcasts/type-parameters/neg/1.kt

diff --git a/compiler/tests-spec/testData/diagnostics/notLinked/contracts/analysis/smartcasts/type-parameters/neg/1.kt b/compiler/tests-spec/testData/diagnostics/notLinked/contracts/analysis/smartcasts/type-parameters/neg/1.kt
new file mode 100644
index 0000000..f98f5d5
--- /dev/null
+++ b/compiler/tests-spec/testData/diagnostics/notLinked/contracts/analysis/smartcasts/type-parameters/neg/1.kt
@@ -0,0 +1,43 @@
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts, kotlin.RequiresOptIn
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS NOT LINKED SPEC TEST (NEGATIVE)
+ *
+ * SECTIONS: contracts, analysis, smartcasts, type-parameters
+ * NUMBER: 1
+ * DESCRIPTION: Smartcasts using Returns effects with simple type checking, not-null conditions and custom condition (condition for smartcast outside contract).
+ * HELPERS: contractFunctions
+ */
+
+/*
+ * TESTCASE NUMBER: 1
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-41078
+ */
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
+
+sealed class Maybe<T> {
+    class Value<T>(val value: T) : Maybe<T>()
+}
+
+@OptIn(ExperimentalContracts::class)
+fun <T> check(x: Maybe<T>): Boolean {
+    contract {
+        returns(true) implies (x is Maybe.Value<T>)
+    }
+    return true
+}
+
+fun test(x: Maybe<Int>) {
+    if (x is Maybe.Value<Int>) {
+        val v: Int = <!NI;DEBUG_INFO_SMARTCAST!>x<!>.value // smartcast to Int
+    }
+    if (check(x)) {
+        val v: Int = <!NI;TYPE_MISMATCH!><!NI;DEBUG_INFO_SMARTCAST!>x<!>.value<!> // smartcast to T (!)
+    }
+}
+

compiler/tests-spec/testData/diagnostics/notLinked/contracts/analysis/smartcasts/type-parameters/neg/2.kt

diff --git a/compiler/tests-spec/testData/diagnostics/notLinked/contracts/analysis/smartcasts/type-parameters/neg/2.kt b/compiler/tests-spec/testData/diagnostics/notLinked/contracts/analysis/smartcasts/type-parameters/neg/2.kt
new file mode 100644
index 0000000..72efd3c
--- /dev/null
+++ b/compiler/tests-spec/testData/diagnostics/notLinked/contracts/analysis/smartcasts/type-parameters/neg/2.kt
@@ -0,0 +1,44 @@
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts, kotlin.RequiresOptIn
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS NOT LINKED SPEC TEST (NEGATIVE)
+ *
+ * SECTIONS: contracts, analysis, smartcasts, type-parameters
+ * NUMBER: 2
+ * DESCRIPTION: Smartcasts using Returns effects with simple type checking, not-null conditions and custom condition (condition for smartcast outside contract).
+ * HELPERS: contractFunctions
+ */
+
+/*
+ * TESTCASE NUMBER: 1
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-41576
+ */
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
+
+
+sealed class Maybe<T> {
+    class Value<T>(val value: T) : Maybe<T>()
+}
+
+fun test(x: Maybe<Int>, y: Any) {
+
+    if (check(y <!NI;UNCHECKED_CAST!>as Maybe<Int><!> )) { //UNCHECKED_CAST
+        val v: Int = y.<!NI;UNRESOLVED_REFERENCE!>value<!> //Maybe<Int> (smart cast from Any), value:UNRESOLVED_REFERENCE
+    }
+    if (check(x <!NI;USELESS_CAST!>as Maybe<Int><!> )) { // USELESS_CAST
+        val v: Int = x.<!NI;UNRESOLVED_REFERENCE!>value<!> // value: UNRESOLVED_REFERENCE instead of smartcast to T
+    }
+}
+
+@OptIn(ExperimentalContracts::class)
+fun <T> check(x: Maybe<T>): Boolean {
+    contract {
+        returns() implies (x is Maybe.Value<T>)
+    }
+    return true
+}