feat(execution): consider string members to violate requirements when…

… empty or whitespace

source/Nuke.Build/Execution/DelegateRequirementService.cs

@@ -25,21 +25,21 @@ public static void ValidateRequirements(INukeBuild build, IReadOnlyCollection<Ex
  if (requirement is Expression<Func<bool>> boolExpression)
  // TODO: same as HasSkippingCondition.GetSkipReason
  Assert.True(boolExpression.Compile().Invoke(), $"Target '{target.Name}' requires '{requirement.Body}'");
- else if (IsMemberNull(requirement.GetMemberInfo(), build, target))
- Assert.Fail($"Target '{target.Name}' requires member '{GetMemberName(requirement.GetMemberInfo())}' to be not null");
+ else if (IsMemberNullOrEmpty(requirement.GetMemberInfo(), build, target))
+ Assert.Fail($"Target '{target.Name}' requires member '{GetMemberName(requirement.GetMemberInfo())}' to be not null or empty");
  }
 
  var requiredMembers = ValueInjectionUtility.GetInjectionMembers(build.GetType())
  .Select(x => x.Member)
  .Where(x => x.HasCustomAttribute<RequiredAttribute>());
  foreach (var member in requiredMembers)
  {
- if (IsMemberNull(member, build))
- Assert.Fail($"Member '{GetMemberName(member)}' is required to be not null");
+ if (IsMemberNullOrEmpty(member, build))
+ Assert.Fail($"Member '{GetMemberName(member)}' is required to be not null or empty");
  }
  }
 
- private static bool IsMemberNull(MemberInfo member, INukeBuild build, ExecutableTarget target = null)
+ private static bool IsMemberNullOrEmpty(MemberInfo member, INukeBuild build, ExecutableTarget target = null)
  {
  member = member.DeclaringType != build.GetType()
  ? build.GetType().GetMember(member.Name).SingleOrDefault() ?? member
@@ -52,7 +52,9 @@ private static bool IsMemberNull(MemberInfo member, INukeBuild build, Executable
  if (build.Host is Terminal)
  TryInjectValueInteractive(member, build);
 
- return member.GetValue(build) == null;
+ return member.GetMemberType() != typeof(string)
+ ? member.GetValue(build) == null
+ : member.GetValue<string>(build).IsNullOrWhiteSpace();
  }
 
  private static void TryInjectValueInteractive(MemberInfo member, INukeBuild build)