Log log_file_path warning only once (#1064)

Avoid printing the warning more than once if `log_file_path` is called
more than once. Only print the warning once to avoid confusion.

Fixes #776

.changesets/print-log-path-warning-only-once.md

@@ -0,0 +1,6 @@
+---
+bump: "patch"
+type: "change"
+---
+
+If the gem can't find a valid log path in the app's `log/` directory, it will no longer print the warning more than once.

lib/appsignal/config.rb

@@ -320,20 +320,29 @@ def log_level
     end
 
     def log_file_path
+      return @log_file_path if defined? @log_file_path
+
       path = config_hash[:log_path] || (root_path && File.join(root_path, "log"))
-      return File.join(File.realpath(path), "appsignal.log") if path && File.writable?(path)
+      if path && File.writable?(path)
+        @log_file_path = File.join(File.realpath(path), "appsignal.log")
+        return @log_file_path
+      end
 
       system_tmp_dir = self.class.system_tmp_dir
       if File.writable? system_tmp_dir
         $stdout.puts "appsignal: Unable to log to '#{path}'. Logging to " \
-          "'#{system_tmp_dir}' instead. Please check the " \
-          "permissions for the application's (log) directory."
-        File.join(system_tmp_dir, "appsignal.log")
+          "'#{system_tmp_dir}' instead. " \
+          "Please check the permissions for the application's (log) " \
+          "directory."
+        @log_file_path = File.join(system_tmp_dir, "appsignal.log")
       else
         $stdout.puts "appsignal: Unable to log to '#{path}' or the " \
           "'#{system_tmp_dir}' fallback. Please check the permissions " \
           "for the application's (log) directory."
+        @log_file_path = nil
       end
+
+      @log_file_path
     end
 
     def valid?

spec/lib/appsignal/config_spec.rb

@@ -757,19 +757,22 @@
     let(:out_stream) { std_stream }
     let(:output) { out_stream.read }
     let(:config) { project_fixture_config("production", :log_path => log_path) }
-    subject { capture_stdout(out_stream) { config.log_file_path } }
+
+    def log_file_path
+      capture_stdout(out_stream) { config.log_file_path }
+    end
 
     context "when path is writable" do
       let(:log_path) { File.join(tmp_dir, "writable-path") }
       before { FileUtils.mkdir_p(log_path, :mode => 0o755) }
       after { FileUtils.rm_rf(log_path) }
 
       it "returns log file path" do
-        expect(subject).to eq File.join(log_path, "appsignal.log")
+        expect(log_file_path).to eq File.join(log_path, "appsignal.log")
       end
 
       it "prints no warning" do
-        subject
+        log_file_path
         expect(output).to be_empty
       end
     end
@@ -783,28 +786,47 @@
         before { FileUtils.chmod(0o777, system_tmp_dir) }
 
         it "returns returns the tmp location" do
-          expect(subject).to eq(File.join(system_tmp_dir, "appsignal.log"))
+          expect(log_file_path).to eq(File.join(system_tmp_dir, "appsignal.log"))
         end
 
         it "prints a warning" do
-          subject
+          log_file_path
           expect(output).to include "appsignal: Unable to log to '#{log_path}'. " \
             "Logging to '#{system_tmp_dir}' instead."
         end
+
+        it "prints a warning once" do
+          capture_stdout(out_stream) do
+            log_file_path
+            log_file_path
+          end
+          message = "appsignal: Unable to log to '#{log_path}'. " \
+            "Logging to '#{system_tmp_dir}' instead."
+          expect(output.scan(message).count).to eq(1)
+        end
       end
 
       context "when the /tmp fallback path is not writable" do
         before { FileUtils.chmod(0o555, system_tmp_dir) }
 
         it "returns nil" do
-          expect(subject).to be_nil
+          expect(log_file_path).to be_nil
         end
 
         it "prints a warning" do
-          subject
+          log_file_path
           expect(output).to include "appsignal: Unable to log to '#{log_path}' " \
             "or the '#{system_tmp_dir}' fallback."
         end
+
+        it "prints a warning once" do
+          capture_stdout(out_stream) do
+            log_file_path
+            log_file_path
+          end
+          message = "appsignal: Unable to log to '#{log_path}' or the '#{system_tmp_dir}' fallback."
+          expect(output.scan(message).count).to eq(1)
+        end
       end
     end
 
@@ -819,11 +841,11 @@
 
       context "when root_path is set" do
         it "returns returns the project log location" do
-          expect(subject).to eq File.join(config.root_path, "log/appsignal.log")
+          expect(log_file_path).to eq File.join(config.root_path, "log/appsignal.log")
         end
 
         it "prints no warning" do
-          subject
+          log_file_path
           expect(output).to be_empty
         end
       end
@@ -883,7 +905,7 @@
           end
 
           it "returns real path of log path" do
-            expect(subject).to eq(File.join(real_path, "appsignal.log"))
+            expect(log_file_path).to eq(File.join(real_path, "appsignal.log"))
           end
         end
       end