[inline-completion] ML-1632: add some tests to the platform

GitOrigin-RevId: d94f8fe8e0c7d10234e9ad727e1f9c1d9932c464

platform/platform-impl/src/com/intellij/codeInsight/inline/completion/InlineCompletionHandler.kt

@@ -245,7 +245,7 @@ class InlineCompletionHandler(
 
   private fun getProvider(event: InlineCompletionEvent): InlineCompletionProvider? {
     if (application.isUnitTestMode && testProvider != null) {
-      return testProvider
+      return testProvider?.takeIf { it.isEnabled(event) }
     }
 
     return InlineCompletionProvider.extensions().firstOrNull {
@@ -335,6 +335,12 @@ class InlineCompletionHandler(
       testProvider = provider
     }
 
+    @TestOnly
+    fun registerTestHandler(provider: InlineCompletionProvider, disposable: Disposable) {
+      registerTestHandler(provider)
+      disposable.whenDisposed { unRegisterTestHandler() }
+    }
+
     @TestOnly
     fun unRegisterTestHandler() {
       testProvider = null

platform/platform-impl/src/com/intellij/codeInsight/inline/completion/session/InlineCompletionContext.kt

@@ -54,6 +54,15 @@ class InlineCompletionContext internal constructor(val editor: Editor, val langu
     isDisposed = true
   }
 
+  override fun toString(): String {
+    return if (!isDisposed) {
+      "InlineCompletionContext(disposed=false, textToInsert=${textToInsert()})"
+    }
+    else {
+      "InlineCompletionContext(disposed=true)"
+    }
+  }
+
   private inline fun <T> assureNotDisposed(block: () -> T): T {
     check(!isDisposed) { "Context is disposed. Cannot access elements." }
     return block()

platform/platform-tests/testSrc/com/intellij/codeInsight/inline/completion/SimpleInlineCompletionTest.kt

@@ -0,0 +1,100 @@
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.codeInsight.inline.completion
+
+import com.intellij.codeInsight.inline.completion.elements.InlineCompletionElement
+import com.intellij.codeInsight.inline.completion.elements.InlineCompletionGrayTextElement
+import com.intellij.codeInsight.inline.completion.elements.InlineCompletionSkipTextElement
+import com.intellij.openapi.fileTypes.PlainTextFileType
+import com.intellij.testFramework.fixtures.BasePlatformTestCase
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+
+@RunWith(JUnit4::class)
+internal class SimpleInlineCompletionTest : BasePlatformTestCase() {
+
+  private fun registerSuggestion(vararg suggestion: InlineCompletionElement) {
+    InlineCompletionHandler.registerTestHandler(SimpleInlineCompletionProvider(suggestion.toList()), testRootDisposable)
+  }
+
+  // !!! VERY IMPORTANT !!!
+  override fun runInDispatchThread(): Boolean {
+    return false
+  }
+
+  @Test
+  fun `test inline completion renders on typings`() = myFixture.testInlineCompletion {
+    init(PlainTextFileType.INSTANCE, "fu<caret>")
+    registerSuggestion(InlineCompletionGrayTextElement(" main(args: List<String>) { }"))
+
+    typeChar('n') // Type a symbol into the editor
+    delay() // Waiting for request to inline completion to finish
+    assertInlineRender(" main(args: List<String>) { }") // Checking what is shown with inlays
+    insert()
+    assertFileContent("fun main(args: List<String>) { }<caret>")
+    assertInlineHidden()
+  }
+
+  @Test
+  fun `test inline completion does not render on direct action call`() = myFixture.testInlineCompletion {
+    init(PlainTextFileType.INSTANCE, "")
+    registerSuggestion(InlineCompletionGrayTextElement("This is tutorial"))
+    callInlineCompletion() // Direct action call
+    delay()
+    assertInlineHidden()
+  }
+
+  @Test
+  fun `test inline completion renders skip elements`() = myFixture.testInlineCompletion {
+    init(PlainTextFileType.INSTANCE, "<caret>)")
+    registerSuggestion(
+      InlineCompletionGrayTextElement("1"),
+      InlineCompletionSkipTextElement(")"),
+      InlineCompletionGrayTextElement(" + (2)")
+    )
+    typeChar('(')
+    assertFileContent("(<caret>)")
+    delay()
+
+    assertInlineElements {
+      gray("1")
+      skip(")")
+      gray(" + (2)")
+    }
+    insert()
+    assertFileContent("(1) + (2)<caret>")
+    assertInlineHidden()
+  }
+
+  @Test
+  fun `test inline completion simple over typing`() = myFixture.testInlineCompletion {
+    init(PlainTextFileType.INSTANCE, "<caret>")
+    registerSuggestion(InlineCompletionGrayTextElement("his is tutorial"))
+    typeChar('T')
+    delay()
+    assertInlineRender("his is tutorial")
+    typeChar('h') // No 'delay' as this update is called instantly
+    assertInlineRender("is is tutorial")
+    typeChar('i')
+    assertInlineRender("s is tutorial")
+
+    assertFileContent("Thi<caret>")
+    insert()
+    assertFileContent("This is tutorial<caret>")
+    assertInlineHidden()
+  }
+
+  private class SimpleInlineCompletionProvider(val suggestion: List<InlineCompletionElement>) : InlineCompletionProvider {
+    override val id: InlineCompletionProviderID = InlineCompletionProviderID("SimpleInlineCompletionProvider")
+
+    override suspend fun getSuggestion(request: InlineCompletionRequest): InlineCompletionSuggestion {
+      return InlineCompletionSuggestion.withFlow {
+        suggestion.forEach { emit(it) }
+      }
+    }
+
+    override fun isEnabled(event: InlineCompletionEvent): Boolean {
+      return event is InlineCompletionEvent.DocumentChange
+    }
+  }
+}

platform/testFramework/src/com/intellij/codeInsight/inline/completion/InlineCompletionLifecycleTestDSL.kt

@@ -343,6 +343,14 @@ class InlineCompletionLifecycleTestDSL(val fixture: CodeInsightTestFixture) {
   }
 }
 
+/**
+ * This is **Experimental API**.
+ *
+ * If you use this DSL to write a test in JUnit3 or JUnit4 test classes, **please set `runInDispatchThread` to `false`**, otherwise, you'll
+ * get a deadlock.
+ *
+ * Example: [com.intellij.codeInsight.inline.completion.SimpleInlineCompletionTest]
+ */
 @ApiStatus.Experimental
 fun CodeInsightTestFixture.testInlineCompletion(
   timeout: Duration = DEFAULT_TEST_TIMEOUT,