support kotlin

app/build.gradle

@@ -13,6 +13,7 @@ repositories {
     maven { url "http://dl.bintray.com/piasy/maven" }
 }
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
 
 def dbflow_version = "4.0.0-beta2"
 def ciName = isEmpty(System.getenv("TRAVIS_TAG")) ? "Staging" : System.getenv("TRAVIS_TAG")
@@ -107,4 +108,7 @@ dependencies {
     implementation 'com.weiwangcn.betterspinner:library-material:1.1.0'
 
     implementation 'com.android.support.constraint:constraint-layout:1.0.2'
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+
+    testImplementation "org.mockito:mockito-core:2.+"
 }

app/src/test/java/org/houxg/leamonax/FileUtilsTest.kt

@@ -0,0 +1,37 @@
+package org.houxg.leamonax
+
+import junit.framework.Assert
+import org.houxg.leamonax.utils.FileUtils
+import org.junit.Before
+import org.junit.Test
+import org.mockito.Mockito.`when`
+import org.mockito.Mockito.mock
+import java.io.File
+
+class FileUtilsTest {
+
+    @Before
+    fun setUp() {
+
+    }
+
+    @Test
+    fun testIsImageFile() {
+        Assert.assertEquals(true, FileUtils.isImageFile(getMockFile("a.jpeg", true)))
+        Assert.assertEquals(true, FileUtils.isImageFile(getMockFile("a.jpg", true)))
+        Assert.assertEquals(true, FileUtils.isImageFile(getMockFile("a.png", true)))
+        Assert.assertEquals(true, FileUtils.isImageFile(getMockFile("a.gif", true)))
+
+        Assert.assertEquals(true, FileUtils.isImageFile(getMockFile("a.JPEG", true)))
+        Assert.assertEquals(true, FileUtils.isImageFile(getMockFile("a.JPG", true)))
+        Assert.assertEquals(true, FileUtils.isImageFile(getMockFile("a.PNG", true)))
+        Assert.assertEquals(true, FileUtils.isImageFile(getMockFile("a.GIF", true)))
+    }
+
+    private fun getMockFile(name: String, isFile: Boolean): File {
+        val mock = mock(File::class.java)
+        `when`(mock.isFile).thenReturn(isFile)
+        `when`(mock.name).thenReturn(name)
+        return mock
+    }
+}

build.gradle

@@ -1,12 +1,14 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
+    ext.kotlin_version = '1.3.11'
     repositories {
         jcenter()
         google()
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:3.2.1'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files