Add "demo" backend

app/k9mail/build.gradle

@@ -13,6 +13,7 @@ dependencies {
     implementation project(":backend:imap")
     implementation project(":backend:pop3")
     implementation project(":backend:webdav")
+    debugImplementation project(":backend:demo")
 
     implementation "androidx.appcompat:appcompat:${versions.androidxAppCompat}"
     implementation "androidx.core:core-ktx:${versions.androidxCore}"

app/k9mail/src/debug/java/app/k9mail/dev/DebugConfig.kt

@@ -0,0 +1,12 @@
+package app.k9mail.dev
+
+import org.koin.core.module.Module
+import org.koin.core.scope.Scope
+
+fun Scope.developmentBackends() = mapOf(
+    "demo" to get<DemoBackendFactory>()
+)
+
+fun Module.developmentModuleAdditions() {
+    single { DemoBackendFactory(backendStorageFactory = get()) }
+}

app/k9mail/src/debug/java/app/k9mail/dev/DemoBackendFactory.kt

@@ -0,0 +1,14 @@
+package app.k9mail.dev
+
+import app.k9mail.backend.demo.DemoBackend
+import com.fsck.k9.Account
+import com.fsck.k9.backend.BackendFactory
+import com.fsck.k9.backend.api.Backend
+import com.fsck.k9.mailstore.K9BackendStorageFactory
+
+class DemoBackendFactory(private val backendStorageFactory: K9BackendStorageFactory) : BackendFactory {
+    override fun createBackend(account: Account): Backend {
+        val backendStorage = backendStorageFactory.createBackendStorage(account)
+        return DemoBackend(backendStorage)
+    }
+}

app/k9mail/src/main/java/com/fsck/k9/backends/KoinModule.kt

@@ -1,5 +1,7 @@
 package com.fsck.k9.backends
 
+import app.k9mail.dev.developmentBackends
+import app.k9mail.dev.developmentModuleAdditions
 import com.fsck.k9.backend.BackendManager
 import com.fsck.k9.backend.imap.BackendIdleRefreshManager
 import com.fsck.k9.backend.imap.SystemAlarmManager
@@ -13,7 +15,7 @@ val backendsModule = module {
                 "imap" to get<ImapBackendFactory>(),
                 "pop3" to get<Pop3BackendFactory>(),
                 "webdav" to get<WebDavBackendFactory>()
-            )
+            ) + developmentBackends()
         )
     }
     single {
@@ -30,4 +32,6 @@ val backendsModule = module {
     single<IdleRefreshManager> { BackendIdleRefreshManager(alarmManager = get()) }
     single { Pop3BackendFactory(get(), get()) }
     single { WebDavBackendFactory(get(), get(), get()) }
+
+    developmentModuleAdditions()
 }

app/k9mail/src/release/java/app/k9mail/dev/ReleaseConfig.kt

@@ -0,0 +1,9 @@
+package app.k9mail.dev
+
+import com.fsck.k9.backend.BackendFactory
+import org.koin.core.module.Module
+import org.koin.core.scope.Scope
+
+fun Scope.developmentBackends() = emptyMap<String, BackendFactory>()
+
+fun Module.developmentModuleAdditions() = Unit

app/ui/legacy/src/debug/java/com/fsck/k9/ui/settings/ExtraAccountDiscovery.kt

@@ -0,0 +1,27 @@
+package com.fsck.k9.ui.settings
+
+import com.fsck.k9.mail.AuthType
+import com.fsck.k9.mail.ConnectionSecurity
+import com.fsck.k9.mail.ServerSettings
+import com.fsck.k9.ui.ConnectionSettings
+
+object ExtraAccountDiscovery {
+    @JvmStatic
+    fun discover(email: String): ConnectionSettings? {
+        return if (email.endsWith("@k9mail.example")) {
+            val serverSettings = ServerSettings(
+                type = "demo",
+                host = "irrelevant",
+                port = 23,
+                connectionSecurity = ConnectionSecurity.SSL_TLS_REQUIRED,
+                authenticationType = AuthType.AUTOMATIC,
+                username = "irrelevant",
+                password = "irrelevant",
+                clientCertificateAlias = null
+            )
+            ConnectionSettings(incoming = serverSettings, outgoing = serverSettings)
+        } else {
+            null
+        }
+    }
+}

app/ui/legacy/src/main/java/com/fsck/k9/account/AccountCreator.kt

@@ -20,6 +20,7 @@ class AccountCreator(private val preferences: Preferences, private val resources
             Protocols.IMAP -> DeletePolicy.ON_DELETE
             Protocols.POP3 -> DeletePolicy.NEVER
             Protocols.WEBDAV -> DeletePolicy.ON_DELETE
+            "demo" -> DeletePolicy.ON_DELETE
             else -> throw AssertionError("Unhandled case: $type")
         }
     }

app/ui/legacy/src/main/java/com/fsck/k9/activity/setup/AccountSetupBasics.java

@@ -32,6 +32,7 @@
 import com.fsck.k9.mailstore.SpecialLocalFoldersCreator;
 import com.fsck.k9.ui.R;
 import com.fsck.k9.ui.ConnectionSettings;
+import com.fsck.k9.ui.settings.ExtraAccountDiscovery;
 import com.fsck.k9.view.ClientCertificateSpinner;
 import com.fsck.k9.view.ClientCertificateSpinner.OnClientCertificateChangedListener;
 import com.google.android.material.textfield.TextInputEditText;
@@ -280,6 +281,12 @@ private void onNext() {
 
         String email = mEmailView.getText().toString();
 
+        ConnectionSettings extraConnectionSettings = ExtraAccountDiscovery.discover(email);
+        if (extraConnectionSettings != null) {
+            finishAutoSetup(extraConnectionSettings);
+            return;
+        }
+
         ConnectionSettings connectionSettings = providersXmlDiscoveryDiscover(email, DiscoveryTarget.INCOMING_AND_OUTGOING);
         if (connectionSettings != null) {
             finishAutoSetup(connectionSettings);

app/ui/legacy/src/release/java/com/fsck/k9/ui/settings/ExtraAccountDiscovery.kt

@@ -0,0 +1,8 @@
+package com.fsck.k9.ui.settings
+
+import com.fsck.k9.ui.ConnectionSettings
+
+object ExtraAccountDiscovery {
+    @JvmStatic
+    fun discover(email: String): ConnectionSettings? = null
+}

backend/demo/build.gradle

@@ -0,0 +1,50 @@
+apply plugin: 'com.android.library'
+apply plugin: 'org.jetbrains.kotlin.android'
+apply plugin: 'kotlin-kapt'
+
+if (rootProject.testCoverage) {
+    apply plugin: 'jacoco'
+}
+
+dependencies {
+    api project(":backend:api")
+
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:${versions.kotlinCoroutines}"
+    implementation "com.jakewharton.timber:timber:${versions.timber}"
+    implementation "com.squareup.moshi:moshi:${versions.moshi}"
+    kapt "com.squareup.moshi:moshi-kotlin-codegen:${versions.moshi}"
+
+    testImplementation project(":mail:testing")
+    testImplementation "junit:junit:${versions.junit}"
+    testImplementation "org.mockito:mockito-core:${versions.mockito}"
+    testImplementation "com.google.truth:truth:${versions.truth}"
+}
+
+android {
+    compileSdkVersion buildConfig.compileSdk
+    buildToolsVersion buildConfig.buildTools
+
+    defaultConfig {
+        minSdkVersion buildConfig.minSdk
+    }
+
+    buildTypes {
+        debug {
+            testCoverageEnabled rootProject.testCoverage
+        }
+    }
+
+    lintOptions {
+        abortOnError false
+        lintConfig file("$rootProject.projectDir/config/lint/lint.xml")
+    }
+
+    compileOptions {
+        sourceCompatibility javaVersion
+        targetCompatibility javaVersion
+    }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
+}

backend/demo/src/main/AndroidManifest.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest package="app.k9mail.backend.demo" />