From 7690074cab2ee8d952a907c7ea53de4773013809 Mon Sep 17 00:00:00 2001
From: Stuart Frost <stuart.2.frost@bt.com>
Date: Fri, 4 Aug 2023 21:48:35 +0100
Subject: [PATCH] Conditionally add !lib to default globs

---
 spec/ameba/config_spec.cr | 20 +++++++++++++++-----
 src/ameba/config.cr       |  9 ++++++++-
 src/ameba/glob_utils.cr   |  3 +--
 3 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/spec/ameba/config_spec.cr b/spec/ameba/config_spec.cr
index 1c1d10b2..844e88fd 100644
--- a/spec/ameba/config_spec.cr
+++ b/spec/ameba/config_spec.cr
@@ -9,10 +9,20 @@ module Ameba
     end
 
     describe ".new" do
-      it "loads default globs when config is empty" do
-        yml = YAML.parse "{}"
-        config = Config.new(yml)
-        config.globs.should eq Config::DEFAULT_GLOBS
+      context "when config is empty" do
+        it "loads default globs" do
+          yml = YAML.parse "{}"
+          config = Config.new(yml)
+          config.globs.should eq ["**/*.cr"]
+        end
+
+        it "only sets !lib as a default glob when there are .cr files in lib" do
+          File.touch "lib/shard.cr"
+          yml = YAML.parse "{}"
+          config = Config.new(yml)
+          config.globs.should eq Config::DEFAULT_GLOBS
+          File.delete "lib/shard.cr"
+        end
       end
 
       it "initializes globs as string" do
@@ -102,7 +112,7 @@ module Ameba
       config = Config.load config_sample
 
       it "holds source globs" do
-        config.globs.should eq Config::DEFAULT_GLOBS
+        config.globs.should eq ["**/*.cr"]
       end
 
       it "allows to set globs" do
diff --git a/src/ameba/config.cr b/src/ameba/config.cr
index 821fa065..7d4480c1 100644
--- a/src/ameba/config.cr
+++ b/src/ameba/config.cr
@@ -95,7 +95,7 @@ class Ameba::Config
     @rules = Rule.rules.map &.new(config).as(Rule::Base)
     @rule_groups = @rules.group_by &.group
     @excluded = load_array_section(config, "Excluded")
-    @globs = load_array_section(config, "Globs", DEFAULT_GLOBS)
+    @globs = load_array_section(config, "Globs", default_globs)
 
     return unless formatter_name = load_formatter_name(config)
     self.formatter = formatter_name
@@ -239,6 +239,13 @@ class Ameba::Config
     end
   end
 
+  private def default_globs
+    DEFAULT_GLOBS.select do |glob|
+      !Dir[glob].empty? ||
+        (glob.starts_with?("!") && !Dir["#{glob[1..-1]}/**/*.cr"].empty?)
+    end
+  end
+
   # :nodoc:
   module RuleConfig
     # Define rule properties
diff --git a/src/ameba/glob_utils.cr b/src/ameba/glob_utils.cr
index 5a0e5c72..df4e80bd 100644
--- a/src/ameba/glob_utils.cr
+++ b/src/ameba/glob_utils.cr
@@ -21,9 +21,8 @@ module Ameba
     # ```
     def expand(globs)
       globs.flat_map do |glob|
-        raise ArgumentError.new("No files found matching #{glob}") if Dir[glob].empty?
-
         glob += "/**/*.cr" if File.directory?(glob)
+        raise ArgumentError.new("No files found matching #{glob}") if Dir[glob].empty?
         Dir[glob]
       end.uniq!
     end