test: backfill coverage for MakeMakefile.pkg_config

Merged: https://github.com/ruby/ruby/pull/5436

test/mkmf/test_pkg_config.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: false
+require_relative 'base'
+require 'shellwords'
+
+class TestMkmf
+  class TestPkgConfig < TestMkmf
+    PKG_CONFIG = find_executable0("pkg-config")
+
+    def setup
+      super
+
+      if PKG_CONFIG
+        @fixtures_dir = File.join(Dir.pwd, "fixtures")
+        @fixtures_lib_dir = File.join(@fixtures_dir, "lib")
+        @fixtures_inc_dir = File.join(@fixtures_dir, "include")
+
+        FileUtils.mkdir(@fixtures_dir)
+        File.write("fixtures/test1.pc", <<~EOF)
+          libdir=#{@fixtures_lib_dir}
+          includedir=#{@fixtures_inc_dir}
+
+          Name: test1
+          Description: Test for mkmf pkg-config method
+          Version: 1.2.3
+          Libs: -L${libdir} -ltest1-public
+          Libs.private: -ltest1-private
+          Cflags: -I${includedir}/cflags-I --cflags-other
+        EOF
+
+        @pkg_config_path, ENV["PKG_CONFIG_PATH"] = ENV["PKG_CONFIG_PATH"], File.join(Dir.pwd, "fixtures")
+      end
+    end
+
+    def teardown
+      if PKG_CONFIG
+        ENV["PKG_CONFIG_PATH"] = @pkg_config_path
+      end
+
+      super
+    end
+
+    def test_pkgconfig_with_option_returns_nil_on_error
+      pend("skipping because pkg-config is not installed") unless PKG_CONFIG
+      assert_nil(pkg_config("package-does-not-exist", "exists"), MKMFLOG)
+    end
+
+    def test_pkgconfig_with_libs_option_returns_output
+      pend("skipping because pkg-config is not installed") unless PKG_CONFIG
+      expected = ["-L#{@fixtures_lib_dir}", "-ltest1-public"].sort
+      actual = pkg_config("test1", "libs").shellsplit.sort
+      assert_equal(expected, actual, MKMFLOG)
+    end
+
+    def test_pkgconfig_with_cflags_option_returns_output
+      pend("skipping because pkg-config is not installed") unless PKG_CONFIG
+      expected = ["--cflags-other", "-I#{@fixtures_inc_dir}/cflags-I"].sort
+      actual = pkg_config("test1", "cflags").shellsplit.sort
+      assert_equal(expected, actual, MKMFLOG)
+    end
+  end
+end