transcendental-lisp/src/test/kotlin/interpreter/LispInterpreterTest.kt

package interpreter

import environment.RuntimeEnvironment
import interpreter.InteractiveLispInterpreter.PROMPT
import org.junit.After
import org.junit.Assert.assertEquals
import org.junit.Assert.assertFalse
import org.junit.Assert.assertTrue
import org.junit.Before
import org.junit.Test
import testutil.TestUtilities.createInputStreamFromString
import java.io.ByteArrayOutputStream
import java.io.PrintStream
import java.text.MessageFormat.format
import java.util.HashSet

class LispInterpreterTest {

    companion object {
        private const val TERMINATED = "terminated"
        private val FILE = LispInterpreterTest::class.java.getResource("file.lisp").file
    }

    private var indicatorSet = HashSet<String>()
    private var outputStream = ByteArrayOutputStream()
    private var errorOutputStream = ByteArrayOutputStream()

    private fun setCommonFeatures() {
        LispInterpreterBuilder.setOutput(PrintStream(outputStream))
        LispInterpreterBuilder.setErrorOutput(PrintStream(errorOutputStream))
        LispInterpreterBuilder.setTerminationFunction { }
        LispInterpreterBuilder.setErrorTerminationFunction { indicatorSet.add(TERMINATED) }
    }

    private fun assertTerminated() {
        assertTrue(indicatorSet.contains(TERMINATED))
    }

    private fun assertErrorMessageWritten() {
        assertTrue(errorOutputStream.toByteArray().isNotEmpty())
    }

    @Before
    fun setUp() {
        indicatorSet.clear()
        outputStream.reset()
        errorOutputStream.reset()
        RuntimeEnvironment.reset()
        LispInterpreterBuilder.reset()
    }

    @After
    fun tearDown() {
        RuntimeEnvironment.reset()
        LispInterpreterBuilder.reset()
    }

    @Test
    fun buildInteractiveInterpreter() {
        setCommonFeatures()
        LispInterpreterBuilder.setInput(System.`in`, "stdin")
        val interpreter = LispInterpreterBuilder.build()

        assertTrue(interpreter is InteractiveLispInterpreter)
    }

    @Test
    fun buildNonInteractiveInterpreter() {
        setCommonFeatures()
        LispInterpreterBuilder.setInput(System.`in`, "stdin")
        LispInterpreterBuilder.setNotInteractive()
        val interpreter = LispInterpreterBuilder.build()

        assertFalse(interpreter is InteractiveLispInterpreter)
        assertFalse(interpreter is FileLispInterpreter)
    }

    @Test
    fun buildFileBasedInterpreter() {
        setCommonFeatures()
        LispInterpreterBuilder.useFile(FILE)
        val interpreter = LispInterpreterBuilder.build()

        assertTrue(interpreter is FileLispInterpreter)
    }

    @Test
    fun attemptToBuildInterpreterOnBadFile() {
        setCommonFeatures()
        LispInterpreterBuilder.useFile("does-not-exist.lisp")
        LispInterpreterBuilder.build()

        assertErrorMessageWritten()
        assertTerminated()
    }

    @Test
    fun makeSureDecoratorsAreInitializedWithDefaults() {
        LispInterpreterBuilder.build()

        assertEquals("", RuntimeEnvironment.decoratePrompt(""))
        assertEquals("", RuntimeEnvironment.decorateValueOutput(""))
        assertEquals("", RuntimeEnvironment.decorateWarningOutput(""))
        assertEquals("", RuntimeEnvironment.decorateErrorOutput(""))
        assertEquals("", RuntimeEnvironment.decorateCriticalOutput(""))
    }

    @Test
    fun makeSureDecoratorsAreSetCorrectly() {
        LispInterpreterBuilder.setPromptDecorator { s -> "#$s#" }
        LispInterpreterBuilder.setValueOutputDecorator { s -> "@$s@" }
        LispInterpreterBuilder.setWarningOutputDecorator { s -> "%$s%" }
        LispInterpreterBuilder.setErrorOutputDecorator { s -> "*$s*" }
        LispInterpreterBuilder.setCriticalOutputDecorator { s -> "$$s$" }
        LispInterpreterBuilder.build()

        assertEquals("#x#", RuntimeEnvironment.decoratePrompt("x"))
        assertEquals("@x@", RuntimeEnvironment.decorateValueOutput("x"))
        assertEquals("%x%", RuntimeEnvironment.decorateWarningOutput("x"))
        assertEquals("*x*", RuntimeEnvironment.decorateErrorOutput("x"))
        assertEquals("\$x$", RuntimeEnvironment.decorateCriticalOutput("x"))
    }

    @Test
    fun fileBasedInterpreterWorks_PrintsLastValueOnly() {
        setCommonFeatures()
        LispInterpreterBuilder.useFile(FILE)
        LispInterpreterBuilder.build().interpret()

        assertEquals("PICKLE\n\n", outputStream.toString())
        assertEquals("", errorOutputStream.toString())
    }

    @Test
    fun interactiveInterpreterWorks() {
        setCommonFeatures()
        LispInterpreterBuilder.setInput(createInputStreamFromString("'pickle"), "input")
        LispInterpreterBuilder.build().interpret()

        assertEquals(format("{0}\n{1}\n{0}\n", PROMPT, "PICKLE"), outputStream.toString())
        assertEquals("", errorOutputStream.toString())
    }

    @Test
    fun interpreterHandlesError() {
        setCommonFeatures()
        LispInterpreterBuilder.setNotInteractive()
        LispInterpreterBuilder.setInput(createInputStreamFromString("pickle"), "input")
        LispInterpreterBuilder.build().interpret()

        assertEquals("\n", outputStream.toString())
        assertEquals("[error] symbol PICKLE has no value\n", errorOutputStream.toString())
    }
}