Add blank behavior controls to PropertyResolver.optionalStringProvider (

#1138)

This helps avoid subtle bugs with blank providers

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CHANGELOG.md

@@ -4,6 +4,8 @@ Changelog
 **Unreleased**
 --------------
 
+- Add blank behavior parameters to `PropertyResolver.optionalStringProvider` overloads to specify behavior for blank property values. Default behavior now is to error.
+
 0.23.2
 ------
 

platforms/gradle/better-gradle-properties/api/better-gradle-properties.api

@@ -42,16 +42,26 @@ public final class foundry/gradle/properties/PropertyResolver {
 	public final fun intValue (Ljava/lang/String;I)I
 	public final fun intValue (Ljava/lang/String;Lorg/gradle/api/provider/Provider;)I
 	public static synthetic fun intValue$default (Lfoundry/gradle/properties/PropertyResolver;Ljava/lang/String;IILjava/lang/Object;)I
-	public final fun optionalStringProvider (Ljava/lang/String;)Lorg/gradle/api/provider/Provider;
-	public final fun optionalStringProvider (Ljava/lang/String;Ljava/lang/String;)Lorg/gradle/api/provider/Provider;
-	public static synthetic fun optionalStringProvider$default (Lfoundry/gradle/properties/PropertyResolver;Ljava/lang/String;Ljava/lang/String;ILjava/lang/Object;)Lorg/gradle/api/provider/Provider;
+	public final fun optionalStringProvider (Ljava/lang/String;Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;)Lorg/gradle/api/provider/Provider;
+	public final fun optionalStringProvider (Ljava/lang/String;Ljava/lang/String;Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;)Lorg/gradle/api/provider/Provider;
+	public static synthetic fun optionalStringProvider$default (Lfoundry/gradle/properties/PropertyResolver;Ljava/lang/String;Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;ILjava/lang/Object;)Lorg/gradle/api/provider/Provider;
+	public static synthetic fun optionalStringProvider$default (Lfoundry/gradle/properties/PropertyResolver;Ljava/lang/String;Ljava/lang/String;Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;ILjava/lang/Object;)Lorg/gradle/api/provider/Provider;
 	public final fun optionalStringValue (Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
 	public static synthetic fun optionalStringValue$default (Lfoundry/gradle/properties/PropertyResolver;Ljava/lang/String;Ljava/lang/String;ILjava/lang/Object;)Ljava/lang/String;
 	public final fun providerFor (Ljava/lang/String;)Lorg/gradle/api/provider/Provider;
 	public final fun stringValue (Ljava/lang/String;)Ljava/lang/String;
 	public final fun stringValue (Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
 }
 
+public final class foundry/gradle/properties/PropertyResolver$BlankBehavior : java/lang/Enum {
+	public static final field ERROR Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;
+	public static final field FILTER Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;
+	public static final field NONE Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;
+	public static fun getEntries ()Lkotlin/enums/EnumEntries;
+	public static fun valueOf (Ljava/lang/String;)Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;
+	public static fun values ()[Lfoundry/gradle/properties/PropertyResolver$BlankBehavior;
+}
+
 public final class foundry/gradle/properties/PropertyResolver$Companion {
 	public final fun createForRootProject (Lorg/gradle/api/Project;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Lfoundry/gradle/properties/PropertyResolver;
 	public static synthetic fun createForRootProject$default (Lfoundry/gradle/properties/PropertyResolver$Companion;Lorg/gradle/api/Project;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)Lfoundry/gradle/properties/PropertyResolver;

platforms/gradle/better-gradle-properties/src/main/kotlin/foundry/gradle/properties/PropertyResolver.kt

@@ -115,12 +115,40 @@ public class PropertyResolver(
     return providerFor(key).orNull ?: defaultValue
   }
 
-  public fun optionalStringProvider(key: String): Provider<String> {
-    return optionalStringProvider(key, null)
+  public fun optionalStringProvider(
+    key: String,
+    blankBehavior: BlankBehavior = BlankBehavior.ERROR,
+  ): Provider<String> {
+    return optionalStringProvider(key, null, blankBehavior)
+  }
+
+  public fun optionalStringProvider(
+    key: String,
+    defaultValue: String? = null,
+    blankBehavior: BlankBehavior = BlankBehavior.ERROR,
+  ): Provider<String> {
+    return providerFor(key)
+      .let { defaultValue?.let { providers.provider { defaultValue } } ?: it }
+      .filter {
+        when (blankBehavior) {
+          BlankBehavior.FILTER -> {
+            it.isNotBlank()
+          }
+          BlankBehavior.ERROR -> {
+            it.ifBlank { error("Unexpected blank value for property '$key'") }
+            true
+          }
+          BlankBehavior.NONE -> {
+            true
+          }
+        }
+      }
   }
 
-  public fun optionalStringProvider(key: String, defaultValue: String? = null): Provider<String> {
-    return providerFor(key).let { defaultValue?.let { providers.provider { defaultValue } } ?: it }
+  public enum class BlankBehavior {
+    FILTER,
+    ERROR,
+    NONE,
   }
 
   public companion object {