Preserve bundle-size; backward-compatible with unpadded placeholder. (#4)

* Preserve bundle-size; backward-compatible with unpadded placeholder.

* Preserve size of bundle in characters instead of bytes.

Author: mars

lib/injectable_env.rb

@@ -3,7 +3,7 @@
 
 class InjectableEnv
   DefaultVarMatcher = /^REACT_APP_/
-  Placeholder='{{REACT_APP_VARS_AS_JSON}}'
+  Placeholder = /\{\{REACT_APP_VARS_AS_JSON_*?\}\}/
 
   def self.create(var_matcher=DefaultVarMatcher)
     vars = ENV.find_all {|name,value| var_matcher===name }
@@ -25,10 +25,15 @@ def self.render(*args)
 
   def self.replace(file, *args)
     injectee = IO.read(file)
-    return unless injectee.index(Placeholder)
+    return unless placeholder = injectee.match(Placeholder)
+    placeholder_size = placeholder.to_s.size
 
     env = create(*args)
+    env_size = env.size
+    new_padding = placeholder_size - env_size
+    env = env + (' ' * [new_padding, 0].max)
     head,_,tail = injectee.partition(Placeholder)
+
     injected = head + env + tail
     File.open(file, 'w') do |f|
       f.write(injected)

spec/injectable_env_spec.rb

@@ -5,6 +5,9 @@
 
 RSpec.describe InjectableEnv do
 
+  Placeholder = '{{REACT_APP_VARS_AS_JSON______________________________________________________________________________________________________}}'
+  UnpaddedPlaceholder = '{{REACT_APP_VARS_AS_JSON}}'
+
   describe '.create' do
     it "returns empty object" do
       expect(InjectableEnv.create).to eq('{}')
@@ -63,7 +66,7 @@
 
   describe '.replace' do
     before do
-      ENV['REACT_APP_HELLO'] = "Hello\n\"World\" we \\ prices today"
+      ENV['REACT_APP_HELLO'] = "Hello\n\"World\" we \\ prices today 🌞"
     end
     after do
       ENV.delete 'REACT_APP_HELLO'
@@ -72,14 +75,61 @@
     it "writes into file" do
       begin
         file = Tempfile.new('injectable_env_test')
-        file.write('var injected="{{REACT_APP_VARS_AS_JSON}}"')
+        file.write(%{var injected="#{Placeholder}"})
         file.rewind
 
         InjectableEnv.replace(file.path)
 
-        expected_value='var injected="{\\"REACT_APP_HELLO\\":\\"Hello\\\\n\\\\\"World\\\\\" we \\\\\\\\ prices today\\"}"'
+        expected_value='var injected="{\\"REACT_APP_HELLO\\":\\"Hello\\\\n\\\\\"World\\\\\" we \\\\\\\\ prices today 🌞\\"}'
         actual_value=file.read
-        expect(actual_value).to eq(expected_value)
+        expect(actual_value.index(expected_value)).to eq(0)
+        # Closing double-quote is padded out but still last char.
+        actual_size = actual_value.size
+        expect(actual_value.index(/\"\Z/)).to eq(actual_size-1)
+      ensure
+        if file
+          file.close
+          file.unlink
+        end
+      end
+    end
+
+    it "matches unpadded placeholder" do
+      begin
+        file = Tempfile.new('injectable_env_test')
+        file.write(%{var injected="#{UnpaddedPlaceholder}"})
+        file.rewind
+
+        InjectableEnv.replace(file.path)
+
+        expected_value='var injected="{\\"REACT_APP_HELLO\\":\\"Hello\\\\n\\\\\"World\\\\\" we \\\\\\\\ prices today 🌞\\"}'
+        actual_value=file.read
+        expect(actual_value.index(expected_value)).to eq(0)
+        # Closing double-quote is padded out but still last char.
+        actual_size = actual_value.size
+        expect(actual_value.index(/\"\Z/)).to eq(actual_size-1)
+      ensure
+        if file
+          file.close
+          file.unlink
+        end
+      end
+    end
+
+    it "preserves character length of bundle" do
+      begin
+        placeholder_size = Placeholder.size
+        file = Tempfile.new('injectable_env_test')
+        file.write(Placeholder)
+        file.rewind
+
+        InjectableEnv.replace(file.path)
+
+        expected_value = '{\\"REACT_APP_HELLO\\":\\"Hello\\\\n\\\\\"World\\\\\" we \\\\\\\\ prices today 🌞\\"}'
+        actual_value = file.read
+        replaced_size = actual_value.size
+        expect(replaced_size).to eq(placeholder_size)
+        expect(actual_value.index(expected_value)).to eq(0)
       ensure
         if file
           file.close