From 7213dfd2858f6ed11b5caec70ef247c534296223 Mon Sep 17 00:00:00 2001
From: Jeremy Woertink <jeremywoertink@gmail.com>
Date: Tue, 26 Nov 2024 14:57:16 -0800
Subject: [PATCH] Raise exception when a duplicate key is found when reading
 from a file. Fixes #34 (#36)

---
 spec/parser_spec.cr     |  6 ++++++
 spec/support/.badenv    |  2 ++
 src/lucky_env/errors.cr |  3 +++
 src/lucky_env/parser.cr | 11 ++++++++++-
 4 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 spec/support/.badenv

diff --git a/spec/parser_spec.cr b/spec/parser_spec.cr
index eaa7d6a..01a30c0 100644
--- a/spec/parser_spec.cr
+++ b/spec/parser_spec.cr
@@ -64,6 +64,12 @@ describe LuckyEnv::Parser do
       data["DB_NAME"].should eq "my_app_development"
       data["LITERAL"].should eq "${NOT_EXISTS_ENV}"
     end
+
+    it "raises on duplicate keys detected" do
+      expect_raises(LuckyEnv::DuplicateKeyDetectedError, /Duplicate key HOST found in \.\/spec\/support\/\.badenv/) do
+        parser.read_file("./spec/support/.badenv")
+      end
+    end
   end
 end
 
diff --git a/spec/support/.badenv b/spec/support/.badenv
new file mode 100644
index 0000000..32b681e
--- /dev/null
+++ b/spec/support/.badenv
@@ -0,0 +1,2 @@
+HOST=localhost
+HOST=duplicate_key
\ No newline at end of file
diff --git a/src/lucky_env/errors.cr b/src/lucky_env/errors.cr
index 37aaefb..0cfec27 100644
--- a/src/lucky_env/errors.cr
+++ b/src/lucky_env/errors.cr
@@ -4,4 +4,7 @@ module LuckyEnv
 
   class MissingFileError < Exception
   end
+
+  class DuplicateKeyDetectedError < Exception
+  end
 end
diff --git a/src/lucky_env/parser.cr b/src/lucky_env/parser.cr
index 148f195..e32d67c 100644
--- a/src/lucky_env/parser.cr
+++ b/src/lucky_env/parser.cr
@@ -30,7 +30,16 @@ module LuckyEnv
           next if comment?(string)
           key, value = parse_value(string)
 
-          hash[key] = value
+          if hash.has_key?(key)
+            raise LuckyEnv::DuplicateKeyDetectedError.new <<-ERROR
+            Duplicate key #{key} found in #{file_path}.
+            To ignore a key, place a # at the front of the line like this:
+
+            # YOUR_KEY=ignored_value
+            ERROR
+          else
+            hash[key] = value
+          end
         end
 
         keys = hash.keys