diff --git a/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.1.fir.kt b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.1.fir.kt
new file mode 100644
index 00000000000..c93ce9167bc
--- /dev/null
+++ b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.1.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS:  -IMPLICIT_CAST_TO_ANY -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER -UNUSED_EXPRESSION
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS SPEC TEST (NEGATIVE)
+ *
+ * SPEC VERSION: 0.1-296
+ * PLACE: control--and-data-flow-analysis, control-flow-graph, expressions-1, conditional-expressions -> paragraph 1 -> sentence 1
+ * NUMBER: 1
+ * DESCRIPTION: check if-expressions must have both branches.
+ */
+
+// TESTCASE NUMBER: 1
+
+fun case1() {
+    val b = true
+    val a =  if (b) {
+        "true"
+    }
+}
+
+// TESTCASE NUMBER: 2
+
+fun case2() {
+    val b = true
+    val a = if (b) "true"
+}
diff --git a/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.2.fir.kt b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.2.fir.kt
new file mode 100644
index 00000000000..c2cb54540c0
--- /dev/null
+++ b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.2.fir.kt
@@ -0,0 +1,32 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS:  -IMPLICIT_CAST_TO_ANY -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER -UNUSED_EXPRESSION
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS SPEC TEST (NEGATIVE)
+ *
+ * SPEC VERSION: 0.1-296
+ * PLACE: control--and-data-flow-analysis, control-flow-graph, expressions-1, conditional-expressions -> paragraph 1 -> sentence 1
+ * NUMBER: 2
+ * DESCRIPTION: check if-expressions must have both branches.
+ */
+
+// TESTCASE NUMBER: 1
+
+fun case1() {
+    val b = true
+    val c = true
+    val a = if (b) {
+        "first true"
+    } else if (c) {
+        "else if true"
+    }
+}
+
+// TESTCASE NUMBER: 2
+
+fun case2() {
+    var b = true
+    val c = true
+    val a = if (b) 1 else if (c) 2 else ;
+}
diff --git a/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.3.fir.kt b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.3.fir.kt
new file mode 100644
index 00000000000..5dd3c8bb914
--- /dev/null
+++ b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.3.fir.kt
@@ -0,0 +1,83 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNREACHABLE_CODE -IMPLICIT_CAST_TO_ANY -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER -UNUSED_EXPRESSION
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS SPEC TEST (NEGATIVE)
+ *
+ * SPEC VERSION: 0.1-296
+ * PLACE: control--and-data-flow-analysis, control-flow-graph, expressions-1, conditional-expressions -> paragraph 1 -> sentence 1
+ * NUMBER: 3
+ * DESCRIPTION: check if-expressions must have both branches. (attempt to pass Nothing to if-condition without 'else' key word)
+ */
+
+fun throwExc(b: Boolean): Boolean {
+    if (b) throw Exception()
+    else return false
+}
+
+// TESTCASE NUMBER: 1
+fun case1() {
+    val x1 = if (throwExc(false)) true
+}
+
+
+// TESTCASE NUMBER: 3
+fun case3() {
+    val x1 = if (throwExc(true)) true
+}
+
+/*
+ * TESTCASE NUMBER: 4
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-35510
+ */
+fun case4() {
+    val x1 = if (throw Exception()) true
+
+    val x2 = if (TODO()) true
+
+    val x0 = if (false) true else if (throw Exception()) ;
+
+}
+
+// TESTCASE NUMBER: 5
+fun case5() {
+    var flag: Boolean? = null
+    val x1 = if (flag ?: throw Exception()) true
+}
+
+/*
+ * TESTCASE NUMBER: 6
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-35510
+ */
+fun case6() {
+    val k1 = if(throw Exception());
+}
+
+/*
+ * TESTCASE NUMBER: 7
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-35510
+ */
+fun case7(nothing: Nothing) {
+    val k1 = if(throw Exception())
+<!SYNTAX!><!>}
+
+/*
+ * TESTCASE NUMBER: 8
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-35510
+ */
+fun case8(nothing: Nothing) {
+    val x1 = if (nothing) true
+}
+
+/*
+ * TESTCASE NUMBER: 9
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-35510
+ */fun case9() {
+    val k1 = if(throw Exception())
+<!SYNTAX!><!>}
diff --git a/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.4.fir.kt b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.4.fir.kt
new file mode 100644
index 00000000000..a8080b01fec
--- /dev/null
+++ b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/1.4.fir.kt
@@ -0,0 +1,48 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNREACHABLE_CODE -IMPLICIT_CAST_TO_ANY -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER -UNUSED_EXPRESSION
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS SPEC TEST (NEGATIVE)
+ *
+ * SPEC VERSION: 0.1-296
+ * PLACE: control--and-data-flow-analysis, control-flow-graph, expressions-1, conditional-expressions -> paragraph 1 -> sentence 1
+ * NUMBER: 4
+ * DESCRIPTION: check if-expressions must have both branches. (attempt to pass Nothing to if-condition with 'else' key word)
+ */
+
+// TESTCASE NUMBER: 1
+
+fun case1() {
+    val y0else = if (false) true else ;
+}
+
+/*
+ * TESTCASE NUMBER: 2
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-35510
+ */
+fun case2(nothing: Nothing) {
+    val n1else = if (nothing) true else;
+}
+
+/*
+ * TESTCASE NUMBER: 3
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-35510
+ */
+fun case3(nothing: Nothing) {
+    val n1else = if (nothing) true else
+<!SYNTAX!><!>}
+
+// TESTCASE NUMBER: 4
+
+fun case4(nothing: Nothing) {
+    val x = if (false) else if (nothing) { "foo"} else
+<!SYNTAX!><!>}
+
+// TESTCASE NUMBER: 5
+
+fun case5(nothing: Nothing) {
+    val x = if (false) else if (nothing) { "foo"} else ;
+}
diff --git a/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/2.1.fir.kt b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/2.1.fir.kt
new file mode 100644
index 00000000000..9a7cb03d0f5
--- /dev/null
+++ b/compiler/tests-spec/testData/diagnostics/linked/control--and-data-flow-analysis/control-flow-graph/expressions-1/conditional-expressions/p-1/neg/2.1.fir.kt
@@ -0,0 +1,32 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER -UNUSED_EXPRESSION
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS SPEC TEST (NEGATIVE)
+ *
+ * SPEC VERSION: 0.1-296
+ * PLACE: control--and-data-flow-analysis, control-flow-graph, expressions-1, conditional-expressions -> paragraph 1 -> sentence 2
+ * NUMBER: 1
+ * DESCRIPTION: check any if-statement in kotlin may be trivially turned into such an expression by replacing the missing branch with a kotlin.Unit object expression.
+ * HELPERS: checkType
+ */
+
+// TESTCASE NUMBER: 1
+
+fun case1() {
+    val b = true
+    if (!b) {
+        println("this is statement")
+    }
+    val statement = if (!b) { println("statement could not be assigned") }
+}
+
+// TESTCASE NUMBER: 2
+
+fun case2() {
+    val a = 1
+    val b = 2
+    if (a > b) a else ; //statement
+    val expression: Any = if (a > b) a else ;
+}