check_c_compiler: print output; add a integration test

build_tests/configure/check_c_compiler_find_first.rb

@@ -0,0 +1,3 @@
+configure do
+  check_c_compiler "gcc", "clang"
+end

lib/rscons/configure_op.rb

@@ -33,6 +33,7 @@ module Rscons
     #
     # @return [void]
     def check_c_compiler(ccc)
+      $stdout.write("Checking for C compiler... ")
       if ccc.empty?
         # Default C compiler search array.
         ccc = %w[gcc clang]
@@ -40,6 +41,12 @@ module Rscons
       cc = ccc.find do |cc|
         test_c_compiler(cc)
       end
+      if cc
+        Ansi.write($stdout, :green, cc, "\n")
+      else
+        Ansi.write($stdout, :red, "not found\n")
+        raise ConfigureFailure.new
+      end
     end
 
     private
@@ -67,13 +74,25 @@ module Rscons
       when "clang"
         command = %W[clang -o #{@work_dir}/cfgtest.exe #{@work_dir}/cfgtest.c]
       else
-        raise ConfigureFailure.new("Unknown C compiler (#{cc})")
+        $stderr.puts "Unknown C compiler (#{cc})"
+        raise ConfigureFailure.new
       end
+      _, _, status = log_and_test_command(command)
+      status == 0
+    end
+
+    # Execute a test command and log the result.
+    def log_and_test_command(command)
+      begin
         @log_fh.puts("Command: #{command.join(" ")}")
         stdout, stderr, status = Open3.capture3(*command)
+        @log_fh.puts("Exit status: #{status.to_i}")
         @log_fh.write(stdout)
         @log_fh.write(stderr)
-      status != 0
+        [stdout, stderr, status]
+      rescue Errno::ENOENT
+        ["", "", 127]
+      end
     end
 
   end

spec/build_tests_spec.rb

@@ -1489,6 +1489,16 @@ EOF
       expect(result.stderr).to match /NoMethodError/
       expect(result.status).to_not eq 0
     end
+
+    context "check_c_compiler" do
+      it "finds the first listed C compiler" do
+        test_dir "configure"
+        result = run_rscons(rsconsfile: "check_c_compiler_find_first.rb", op: "configure")
+        expect(result.stderr).to eq ""
+        expect(result.status).to eq 0
+        expect(result.stdout).to match /Checking for C compiler\.\.\. gcc/
+      end
+    end
   end
 
 end