Simplify the empty YAML file detection

Author: adamnfish

core/src/main/scala/com/gu/devenv/Config.scala

@@ -38,24 +38,15 @@ object Config {
       projectConfig <- json.as[ProjectConfig].toTry
     } yield projectConfig
 
-  def parseUserConfig(contents: String): Try[UserConfig] = {
-    // Handle empty files or files with only comments/whitespace
-    def isEmptyOrCommentsOnly(text: String): Boolean = {
-      text.linesIterator
-        .map(_.trim)
-        .filter(_.nonEmpty)
-        .forall(_.startsWith("#"))
-    }
-    
-    if (isEmptyOrCommentsOnly(contents)) {
+  def parseUserConfig(contents: String): Try[UserConfig] =
+    if (yamlIsEmpty(contents)) {
       scala.util.Success(UserConfig(None, None))
     } else {
       for {
         json       <- parser.parse(contents).toTry
         userConfig <- json.as[UserConfig].toTry
       } yield userConfig
     }
-  }
 
   def mergeConfigs(
       projectConfig: ProjectConfig,
@@ -190,6 +181,15 @@ object Config {
       envList.map(env => env.name -> Json.fromString(env.value)): _*
     )
 
+  /** Parsing an empty YAML file throws an exception, but an empty YAML file is valid and should
+    * result in an empty configuration. We check for empty contents here.
+    */
+  private def yamlIsEmpty(text: String): Boolean =
+    text.linesIterator
+      .map(_.trim)
+      .filter(_.nonEmpty)
+      .forall(_.startsWith("#"))
+
   private def applyPlugins(
       projectPlugins: Plugins,
       userPlugins: Option[Plugins]

core/src/main/scala/com/gu/devenv/models.scala

@@ -30,6 +30,9 @@ case class UserConfig(
     plugins: Option[Plugins],
     dotfiles: Option[Dotfiles]
 )
+object UserConfig {
+  val empty = UserConfig(None, None)
+}
 
 enum ForwardPort {
   case SamePort(port: Int)

core/src/test/scala/com/gu/devenv/ConfigTest.scala

@@ -97,11 +97,7 @@ class ConfigTest
       val emptyConfig = ""
       val Success(userConfig) =
         Config.parseUserConfig(emptyConfig).success
-
-      userConfig should have(
-        "plugins" as None,
-        "dotfiles" as None
-      )
+      userConfig shouldBe UserConfig.empty
     }
 
     "parses a user config file with only comments" in {
@@ -111,53 +107,7 @@ class ConfigTest
       val Success(userConfig) =
         Config.parseUserConfig(commentsOnlyConfig).success
 
-      userConfig should have(
-        "plugins" as None,
-        "dotfiles" as None
-      )
-    }
-
-    "parses a user config file with comments and YAML content" in {
-      val configWithComments = """# This is a comment
-                                 |plugins:
-                                 |  intellij:
-                                 |    - "com.example.plugin"
-                                 |  vscode:
-                                 |    - "example.vscode-plugin"
-                                 |""".stripMargin
-      val Success(userConfig) =
-        Config.parseUserConfig(configWithComments).success
-
-      userConfig should have(
-        "plugins" as Some(
-          Plugins(
-            List("com.example.plugin"),
-            List("example.vscode-plugin")
-          )
-        ),
-        "dotfiles" as None
-      )
-    }
-
-    "parses a user config file with inline comments" in {
-      val configWithInlineComments = """plugins:  # User plugins
-                                       |  intellij:
-                                       |    - "com.example.plugin"  # Example plugin
-                                       |  vscode:
-                                       |    - "example.vscode-plugin"
-                                       |""".stripMargin
-      val Success(userConfig) =
-        Config.parseUserConfig(configWithInlineComments).success
-
-      userConfig should have(
-        "plugins" as Some(
-          Plugins(
-            List("com.example.plugin"),
-            List("example.vscode-plugin")
-          )
-        ),
-        "dotfiles" as None
-      )
+      userConfig shouldBe UserConfig.empty
     }
   }