Clean up contributed merge_capture_results: idiomatic ruby

Author: ianfixes

Diff for: lib/arduino_ci/host.rb

@@ -30,21 +30,31 @@ def self.which(cmd)
       nil
     end
 
+    # Execute a shell command and capture stdout, stderr, and status
+    #
+    # @see Process.spawn
+    # @see https://docs.ruby-lang.org/en/2.0.0/Process.html#method-c-spawn
+    # @return [Hash] with keys "stdout" (String), "stderr" (String), and "success" (bool)
     def self.run_and_capture(*args, **kwargs)
       stdout, stderr, status = Open3.capture3(*args, **kwargs)
       { out: stdout, err: stderr, success: status.exitstatus.zero? }
     end
 
-    def self.merge_capture_results(args)
-      result = { out: "", err: "", success: true }
-      args.each do |a|
-        result[:out] = result[:out] + a[:out]
-        result[:err] = result[:err] + a[:err]
-        result[:success] = a[:success] unless a[:success]
-      end
-      result
+    # Merge multiple capture results into one aggregate value
+    #
+    # @param args [Array] Array of hashes from `run_and_capture`
+    # @return [Hash] with keys "stdout" (String), "stderr" (String), and "success" (bool)
+    def self.merge_capture_results(*args)
+      {
+        out: args.map { |a| a[:out] }.join(),
+        err: args.map { |a| a[:err] }.join(),
+        success: args.all? { |a| a[:success] }
+      }
     end
 
+    # Execute a shell command
+    #
+    # @see system
     def self.run_and_output(*args, **kwargs)
       system(*args, **kwargs)
     end

Diff for: spec/host_spec.rb

@@ -76,14 +76,14 @@ def with_tmpdir(path)
       a1 = { out: "one", err: "ONE", success: true }
       a2 = { out: "two", err: "TWO", success: false }
       a3 = { out: "three", err: "THREE", success: true }
-      res = ArduinoCI::Host.merge_capture_results([a1, a2, a3])
+      res = ArduinoCI::Host.merge_capture_results(a1, a2, a3)
       expect(res[:out]).to eq("onetwothree")
       expect(res[:err]).to eq("ONETWOTHREE")
       expect(res[:success]).to eq(false)
     end
 
     it "handles empty input" do
-      res = ArduinoCI::Host.merge_capture_results([])
+      res = ArduinoCI::Host.merge_capture_results()
       expect(res[:out]).to eq("")
       expect(res[:err]).to eq("")
       expect(res[:success]).to eq(true)