[K/JS] Prepare JS Plain Objects plugin to publication

plugins/js-plain-objects/compiler-plugin/testData/diagnostics/inheritance.kt

@@ -0,0 +1,27 @@
+// FIR_IDENTICAL
+// SKIP_TXT
+
+// FILE: test.kt
+import kotlinx.js.JsPlainObject
+
+external interface A
+
+external interface B
+
+external interface C
+
+@JsPlainObject
+external interface D : <!JS_PLAIN_OBJECT_CAN_EXTEND_ONLY_OTHER_JS_PLAIN_OBJECTS!>A<!>, <!JS_PLAIN_OBJECT_CAN_EXTEND_ONLY_OTHER_JS_PLAIN_OBJECTS!>B<!>, <!JS_PLAIN_OBJECT_CAN_EXTEND_ONLY_OTHER_JS_PLAIN_OBJECTS!>C<!>
+
+@JsPlainObject
+external interface E
+
+@JsPlainObject
+external interface F
+
+@JsPlainObject
+external interface DEF: D, E, F
+
+external interface G: A, C, <!IMPLEMENTING_OF_JS_PLAIN_OBJECT_IS_NOT_SUPPORTED!>E<!>
+
+class Foo : A, <!IMPLEMENTING_OF_JS_PLAIN_OBJECT_IS_NOT_SUPPORTED!>D<!>, B

plugins/js-plain-objects/compiler-plugin/testData/diagnostics/only-properties.kt

@@ -0,0 +1,15 @@
+// FIR_IDENTICAL
+// SKIP_TXT
+
+// FILE: test.kt
+import kotlinx.js.JsPlainObject
+
+@JsPlainObject
+external interface Foo {
+    val foo: String
+    val bar: Int?
+    val fn: () -> String
+    val fnOptional: (() -> String)?
+    
+    <!METHODS_ARE_NOT_ALLOWED_INSIDE_JS_PLAIN_OBJECT!>fun test(): String<!>
+}

plugins/js-plain-objects/compiler-plugin/testData/diagnostics/wrongAnnotationTarget.kt

@@ -0,0 +1,28 @@
+// FIR_IDENTICAL
+// SKIP_TXT
+
+// FILE: test.kt
+import kotlinx.js.JsPlainObject
+
+<!NON_EXTERNAL_DECLARATIONS_NOT_SUPPORTED("class")!>@JsPlainObject
+class Regular1<!>
+
+@JsPlainObject
+<!NON_EXTERNAL_DECLARATIONS_NOT_SUPPORTED("object")!>object Regular2<!>
+
+<!NON_EXTERNAL_DECLARATIONS_NOT_SUPPORTED("enum class")!>@JsPlainObject
+enum class Regular3<!>
+
+<!ONLY_INTERFACES_ARE_SUPPORTED("class")!>@JsPlainObject
+external class External1<!>
+
+@JsPlainObject
+external <!ONLY_INTERFACES_ARE_SUPPORTED("object")!>object External2<!>
+
+@JsPlainObject
+external interface External3
+
+external class Nested {
+    @JsPlainObject
+    interface Inner
+}