Test links reference existing files

repo/codebase-tests/tests/org/jetbrains/kotlin/code/LicensesTests.kt

@@ -5,23 +5,25 @@
 
 package org.jetbrains.kotlin.code
 
-import junit.framework.TestCase
 import org.jetbrains.kotlin.test.testFramework.KtUsefulTestCase
+import org.jetbrains.kotlin.test.testFramework.KtUsefulTestCase.assertEmpty
 import org.junit.Test
 import java.io.File
 
 class LicensesTests {
+    companion object {
+        private const val licenseReadmePath = "license/README.md"
+    }
+
     @Test
     fun testLinksDefinitions() {
-        val licenseDir = File("license")
-
         val linkDefinitionRegExp = Regex(pattern = "\\[(\\w+)]:.+")
         val linkRegExp = Regex(pattern = "]\\s?\\[(\\w+)]")
 
         val linksUsages = mutableSetOf<String>()
         val linksDefinitions = mutableSetOf<String>()
 
-        val readmeFile = File(licenseDir, "README.md")
+        val readmeFile = File(licenseReadmePath)
         readmeFile.useLines { lineSequence ->
             lineSequence.forEach { line ->
                 val definitionMatch = linkDefinitionRegExp.matchEntire(line)
@@ -39,4 +41,18 @@ class LicensesTests {
             linksDefinitions.sorted()
         )
     }
+
+    @Test
+    fun testLicensesAreExistingFiles() {
+        val licenseReferenceRegexp = Regex("\\[([^]]*third_party/[^]]*\\.txt)]")
+        val readmeFile = File(licenseReadmePath)
+        val linkedInReadme = readmeFile.useLines { lineSequence ->
+            lineSequence.flatMap { line ->
+                licenseReferenceRegexp.findAll(line).map { it.groups[1]?.value ?: error("Should be present because of match") }
+            }.toSet()
+        }
+
+        val missingFiles = linkedInReadme.filterNot { path -> File(path).exists() }
+        assertEmpty("Files for licenses are missing", missingFiles)
+    }
 }