Fix #3292: Add check for test files presence for prod files (#3343)

* Fix #3290: Add support for generic regex pattern matching

* Apply review suggestions for proto location

* Delete main directory

* Implment script logic and tests

* CI setup part 1

* syntax fix in yaml file

* import nits in dummy file

* Use regex patterns from script in script test

* Make PR suggestions into effect

* Make PR suggestions into effect

* Make PR suggestions into effect

* Improve naming of script_assets variables

* Make PR suggestions into effect

* Make PR suggestions

* Make PR suggestions

* Revamp testing approach

* Fix #3291: Add check for XML syntax correctness

* nit fixes

* Introduce XML syntax check in static checks workflow

* Fix #3292: Add check for test files presence for prod files

* Make nit suggestions

* Make nit suggestions

* Make nit suggestions

* Add ScriptConstants file to exemptions test list

* Add if: always()

* Add if: always()

* Apply review suggestions on PR

* Make review suggestions from regex pattern checks

* Implement review suggestions based on #3340

* Refactor PR as per feedback recieved

* Implement feedback suggestions

* Implement review suggestions

* Implement review suggestions

* Implement review suggestions

* Implement review suggestions

* nits

* Nit fixes

* Nit fixes

* Nit fixes

* nit fix

* nit fix

* Review suggestions part 1

* Implement review suggestions part 2

* nit fixes

* update static_checks

* add test to repository file

* nit fix

* nit fix

* nit fix

* Do review suggestions

* Implement review suggestions

* Implement review suggestions

* nit fix

* Implement review suggestions

* Add Ben as a codeowner for the ScriptExemptions file

* bazel files nit fix

* Introduce a library for the regex assets

* Make directory structure same as that of #3374

* Make directory structure similar to #3374

* add new files to test file script exemptions and nit fixes

* diable ktlint max-line-length

* disable ktlint-max-line

* disable ktlint max-length

* remove testonly attribute from tests

* add new files to script exemptions

* nit fix

* nit fix

* Apply review suggestions

* ktlint fix

* nit fix

* Apply nit fixes

* Apply nit fixes

* Remove script constants

* nit fix

* add todo

* add todo

* nit fixes

* add test

* add testOnly

* nit fixes

* nit fix

* nit fixes

* nit fixes

* nit fixes

* nit fixes

* fix textproto file

* add exemptions to textproto

* sort failures lexicographically

* add new files to exemption list

.github/workflows/static_checks.yml

@@ -113,3 +113,8 @@ jobs:
         if: always()
         run: |
           bazel run //scripts:xml_syntax_check -- $(pwd)
+
+      - name: Testfile Presence Check
+        if: always()
+        run: |
+          bazel run //scripts:test_file_check -- $(pwd)

scripts/BUILD.bazel

@@ -3,7 +3,11 @@ Kotlin-based scripts to help developers or perform continuous integration tasks.
 """
 
 load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_jvm_binary", "kt_jvm_library")
-load("//scripts:script_assets.bzl", "generate_regex_assets_list_from_text_protos")
+load(
+    "//scripts:script_assets.bzl",
+    "generate_regex_assets_list_from_text_protos",
+    "generate_test_file_assets_list_from_text_protos",
+)
 
 # Visibility for libraries that should be accessible to script tests.
 package_group(
@@ -74,3 +78,23 @@ kt_jvm_binary(
     main_class = "org.oppia.android.scripts.xml.XmlSyntaxCheckKt",
     runtime_deps = ["//scripts/src/java/org/oppia/android/scripts/xml:xml_syntax_check_lib"],
 )
+
+TEST_FILE_EXEMPTION_ASSETS = generate_test_file_assets_list_from_text_protos(
+    name = "test_file_exemption_assets",
+    test_file_exemptions_name = ["test_file_exemptions"],
+)
+
+kt_jvm_library(
+    name = "test_file_check_assets",
+    testonly = True,
+    data = TEST_FILE_EXEMPTION_ASSETS,
+    visibility = [":oppia_script_test_visibility"],
+)
+
+kt_jvm_binary(
+    name = "test_file_check",
+    testonly = True,
+    data = TEST_FILE_EXEMPTION_ASSETS,
+    main_class = "org.oppia.android.scripts.testfile.TestFileCheckKt",
+    runtime_deps = ["//scripts/src/java/org/oppia/android/scripts/testfile:test_file_check_lib"],
+)

scripts/script_assets.bzl

@@ -38,3 +38,27 @@ def generate_regex_assets_list_from_text_protos(
         proto_dep_bazel_target_prefix = "//scripts/src/java/org/oppia/android/scripts/proto",
         proto_package = "proto",
     )
+
+def generate_test_file_assets_list_from_text_protos(
+        name,
+        test_file_exemptions_name):
+    """
+    Converts multiple lists of text proto assets to binary.
+
+    Args:
+        name: str. The name of this generation instance. This will be a prefix for derived targets.
+        test_file_exemptions_name: list of str. The list of test file exemptions file names.
+
+    Returns:
+        list of str. The list of new proto binary asset files that were generated.
+    """
+    return generate_proto_binary_assets(
+        name = name,
+        names = test_file_exemptions_name,
+        proto_dep_name = "test_file_exemptions",
+        proto_type_name = "TestFileExemptions",
+        name_prefix = name,
+        asset_dir = "assets",
+        proto_dep_bazel_target_prefix = "//scripts/src/java/org/oppia/android/scripts/proto",
+        proto_package = "proto",
+    )

scripts/src/java/org/oppia/android/scripts/proto/BUILD.bazel

@@ -32,3 +32,15 @@ java_lite_proto_library(
     visibility = ["//scripts:oppia_script_library_visibility"],
     deps = [":file_content_validation_checks_proto"],
 )
+
+proto_library(
+    name = "test_file_exemptions_proto",
+    srcs = ["script_exemptions.proto"],
+    visibility = ["//scripts:oppia_script_binary_visibility"],
+)
+
+java_lite_proto_library(
+    name = "test_file_exemptions_java_proto_lite",
+    visibility = ["//scripts:oppia_script_library_visibility"],
+    deps = [":test_file_exemptions_proto"],
+)

scripts/src/java/org/oppia/android/scripts/proto/script_exemptions.proto

@@ -0,0 +1,21 @@
+syntax = "proto3";
+
+package proto;
+
+option java_package = "org.oppia.android.scripts.proto";
+option java_multiple_files = true;
+
+// Exemptions for the test-file check. Exemptions indicate files for which we should not check for
+// having test files.
+message TestFileExemptions {
+  // List of all the files which should be exempted for the test-file check. For exempting any
+  // file, provide its relative path to root in 'script/assets/test_file_exemptions.textproto'.
+  // Also, note that the file paths in the textproto file are maintained in lexicographical order.
+  // While adding any new file, please add it only at the correct lexicographical position, so that
+  // the list remains sorted.
+  //
+  // For example if we want to add the 'ActivityComponent.kt' file to the exemption list, add:
+  // 'exempted_file_path: "app/src/main/java/org/oppia/android/app/activity/ActivityComponent.kt"'
+  // at the correct lexicographical position in the textproto file.
+  repeated string exempted_file_path = 1;
+}

scripts/src/java/org/oppia/android/scripts/testfile/BUILD.bazel

@@ -0,0 +1,17 @@
+"""
+Libraries corresponding to test file-related checks, such as ensuring that all the production
+(all Kotlin files) files have a corresponding test file present.
+"""
+
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_jvm_library")
+
+kt_jvm_library(
+    name = "test_file_check_lib",
+    testonly = True,
+    srcs = ["TestFileCheck.kt"],
+    visibility = ["//scripts:oppia_script_binary_visibility"],
+    deps = [
+        "//scripts/src/java/org/oppia/android/scripts/common:repository_file",
+        "//scripts/src/java/org/oppia/android/scripts/proto:test_file_exemptions_java_proto_lite",
+    ],
+)

scripts/src/java/org/oppia/android/scripts/testfile/TestFileCheck.kt

@@ -0,0 +1,108 @@
+package org.oppia.android.scripts.testfile
+
+import org.oppia.android.scripts.common.RepositoryFile
+import org.oppia.android.scripts.proto.TestFileExemptions
+import java.io.File
+import java.io.FileInputStream
+
+/**
+ * Script for ensuring that all production files have test files present.
+ *
+ * Usage:
+ *   bazel run //scripts:test_file_check -- <path_to_directory_root>
+ *
+ * Arguments:
+ * - path_to_directory_root: directory path to the root of the Oppia Android repository.
+ *
+ * Example:
+ *   bazel run //scripts:test_file_check -- $(pwd)
+ */
+fun main(vararg args: String) {
+  // Path of the repo to be analyzed.
+  val repoPath = "${args[0]}/"
+
+  val testFileExemptiontextProto = "scripts/assets/test_file_exemptions"
+
+  // A list of all the files to be exempted for this check.
+  // TODO(#3436): Develop a mechanism for permanently exempting files which do not ever need tests.
+  val testFileExemptionList = loadTestFileExemptionsProto(testFileExemptiontextProto)
+    .getExemptedFilePathList()
+
+  // A list of all kotlin files in the repo to be analyzed.
+  val searchFiles = RepositoryFile.collectSearchFiles(
+    repoPath = repoPath,
+    expectedExtension = ".kt",
+    exemptionsList = testFileExemptionList
+  )
+
+  // A list of all the prod files present in the repo.
+  val prodFilesList = searchFiles.filter { file -> !file.name.endsWith("Test.kt") }
+
+  // A list of all the test files present in the repo.
+  val testFilesList = searchFiles.filter { file -> file.name.endsWith("Test.kt") }
+
+  // A list of all the prod files that do not have a corresponding test file.
+  val matchedFiles = prodFilesList.filter { prodFile ->
+    !testFilesList.any { testFile ->
+      testFile.name == computeExpectedTestFileName(prodFile)
+    }
+  }
+
+  logFailures(matchedFiles, testFileExemptiontextProto)
+
+  if (matchedFiles.isNotEmpty()) {
+    throw Exception("TEST FILE CHECK FAILED")
+  } else {
+    println("TEST FILE CHECK PASSED")
+  }
+}
+
+/**
+ * Computes the expected test file name for a prod file.
+ *
+ * @param prodFile the prod file for which expected test file name has to be computed
+ * @return expected name of the test file
+ */
+private fun computeExpectedTestFileName(prodFile: File): String {
+  return "${prodFile.nameWithoutExtension}Test.kt"
+}
+
+/**
+ * Logs the file names of all the prod files that do not have a test file.
+ *
+ * @param matchedFiles list of all the files missing a test file
+ * @param testFileExemptiontextProto the location of the test file exemption textproto file
+ */
+private fun logFailures(matchedFiles: List<File>, testFileExemptiontextProto: String) {
+  if (matchedFiles.isNotEmpty()) {
+    matchedFiles.sorted().forEach { file ->
+      println("File $file does not have a corresponding test file.")
+    }
+    println("If this is correct, please update $testFileExemptiontextProto.textproto")
+    println(
+      "Note that, in general, all new files should have tests. If you choose to add an" +
+        " exemption, please specifically call this out in your PR description."
+    )
+    println()
+  }
+}
+
+/**
+ * Loads the test file exemptions list to proto.
+ *
+ * @param testFileExemptiontextProto the location of the test file exemption textproto file
+ * @return proto class from the parsed textproto file
+ */
+private fun loadTestFileExemptionsProto(testFileExemptiontextProto: String): TestFileExemptions {
+  val protoBinaryFile = File("$testFileExemptiontextProto.pb")
+  val builder = TestFileExemptions.getDefaultInstance().newBuilderForType()
+
+  // This cast is type-safe since proto guarantees type consistency from mergeFrom(),
+  // and this method is bounded by the generic type T.
+  @Suppress("UNCHECKED_CAST")
+  val protoObj: TestFileExemptions =
+    FileInputStream(protoBinaryFile).use {
+      builder.mergeFrom(it)
+    }.build() as TestFileExemptions
+  return protoObj
+}

scripts/src/javatests/org/oppia/android/scripts/testfile/BUILD.bazel

@@ -0,0 +1,18 @@
+"""
+Tests corresponding to test file-related checks, such as ensuring that all the production
+(all Kotlin files) files have a corresponding test file present.
+"""
+
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_jvm_test")
+
+kt_jvm_test(
+    name = "TestFileCheckTest",
+    srcs = ["TestFileCheckTest.kt"],
+    deps = [
+        "//scripts:test_file_check_assets",
+        "//scripts/src/java/org/oppia/android/scripts/testfile:test_file_check_lib",
+        "//testing:assertion_helpers",
+        "//third_party:com_google_truth_truth",
+        "//third_party:org_jetbrains_kotlin_kotlin-test-junit",
+    ],
+)