diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index a3543aec3..6dc399fae 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -26,3 +26,7 @@ A new plugin parses the output of the sysconf command to provide information on
 ## AWS Account ID
 
 The EC2 plugin now fetches the AWS Account ID in addition to previous instance metadata
+
+## GCC Detection
+
+GCC detection has been improved to collect additional information, and to not prompt for the installation of Xcode on macOS systems
diff --git a/lib/ohai/plugins/c.rb b/lib/ohai/plugins/c.rb
index 3dee14928..61b20cc66 100644
--- a/lib/ohai/plugins/c.rb
+++ b/lib/ohai/plugins/c.rb
@@ -16,11 +16,8 @@
 # limitations under the License.
 #
 
-require "rbconfig"
-
 Ohai.plugin(:C) do
   provides "languages/c"
-
   depends "languages"
 
   def collect(cmd, &block)
@@ -34,94 +31,169 @@ def collect(cmd, &block)
     Ohai::Log.debug("Plugin C: '#{cmd}' binary could not be found. Skipping data.")
   end
 
-  collect_data do
-    c = Mash.new
+  def xcode_installed?
+    Ohai::Log.debug("Plugin C: Checking for Xcode Command Line Tools.")
+    so = shell_out("/usr/bin/xcode-select -p")
+    if so.exitstatus == 0
+      Ohai::Log.debug("Plugin C: Xcode Command Line Tools found.")
+      return true
+    else
+      Ohai::Log.debug("Plugin C: Xcode Command Line Tools not found.")
+      return false
+    end
+  rescue Ohai::Exceptions::Exec
+    Ohai::Log.debug("Plugin C: xcode-select binary could not be found. Skipping data.")
+  end
 
-    #gcc
+  def collect_gcc
+    # gcc
+    # Sample output on os x:
+    # Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
+    # Apple LLVM version 7.3.0 (clang-703.0.29)
+    # Target: x86_64-apple-darwin15.4.0
+    # Thread model: posix
+    # InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
+    #
+    #
+    # Sample output on Linux:
+    # Using built-in specs.
+    # COLLECT_GCC=gcc
+    # COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
+    # Target: x86_64-linux-gnu
+    # Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.4' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
+    # Thread model: posix
+    # gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4)
+    gcc = Mash.new
     collect("gcc -v") do |so|
-      # Sample output:
-      # Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
-      # Apple LLVM version 7.3.0 (clang-703.0.29)
-      # Target: x86_64-apple-darwin15.4.0
-      # Thread model: posix
-      # InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
-      description = so.stderr.split($/).last
-      output = description.split
-      if output.length >= 3
-        c[:gcc] = Mash.new
-        c[:gcc][:version] = output[2]
-        c[:gcc][:description] = description
+      so.stderr.each_line do |line|
+        case line
+        when /^(.*version\s(\S*).*)/
+          gcc[:description] = $1
+          gcc[:version] = $2
+        when /^Target:\s(.*)/
+          gcc[:target] = $1
+        when /^Configured with:\s(.*)/
+          gcc[:configured_with] = $1
+        when /^Thread model:\s(.*)/
+          gcc[:thread_model] = $1
+        end
       end
     end
+    @c[:gcc] = gcc unless gcc.empty?
+  end
 
-    #glibc
+  def collect_glibc
+    # glibc
     ["/lib/libc.so.6", "/lib64/libc.so.6"].each do |glibc|
       collect( Ohai.abs_path( glibc )) do |so|
         description = so.stdout.split($/).first
         if description =~ /(\d+\.\d+\.?\d*)/
-          c[:glibc] = Mash.new
-          c[:glibc][:version] = $1
-          c[:glibc][:description] = description
+          @c[:glibc] = Mash.new
+          @c[:glibc][:version] = $1
+          @c[:glibc][:description] = description
         end
-      end unless c[:glibc] || ::RbConfig::CONFIG["host_os"] =~ /mswin|mingw32|windows/
+      end
     end
+  end
 
-    #ms cl
+  def check_for_cl
+    # ms cl
     collect("cl /?") do |so|
       description = so.stderr.lines.first.chomp
       if description =~ /Compiler Version ([\d\.]+)/
-        c[:cl] = Mash.new
-        c[:cl][:version] = $1
-        c[:cl][:description] = description
+        @c[:cl] = Mash.new
+        @c[:cl][:version] = $1
+        @c[:cl][:description] = description
       end
     end
+  end
 
-    #ms vs
+  def check_for_devenv
+    # ms vs
     collect("devenv.com /?") do |so|
       lines = so.stdout.split($/)
       description = lines[0].length == 0 ? lines[1] : lines[0]
       if description =~ /Visual Studio Version ([\d\.]+)/
-        c[:vs] = Mash.new
-        c[:vs][:version] = $1.chop
-        c[:vs][:description] = description
+        @c[:vs] = Mash.new
+        @c[:vs][:version] = $1.chop
+        @c[:vs][:description] = description
       end
     end
+  end
 
-    #ibm xlc
+  def collect_xlc
+    # ibm xlc
     begin
       so = shell_out("xlc -qversion")
       if so.exitstatus == 0 || (so.exitstatus >> 8) == 249
         description = so.stdout.split($/).first
         if description =~ /V(\d+\.\d+)/
-          c[:xlc] = Mash.new
-          c[:xlc][:version] = $1
-          c[:xlc][:description] = description.strip
+          @c[:xlc] = Mash.new
+          @c[:xlc][:version] = $1
+          @c[:xlc][:description] = description.strip
         end
       end
     rescue Ohai::Exceptions::Exec
     end
+  end
 
-    #sun pro
+  def collect_sunpro
+    # sun pro
     collect("cc -V -flags") do |so|
       output = so.stderr.split
       if so.stderr =~ /^cc: Sun C/ && output.size >= 4
-        c[:sunpro] = Mash.new
-        c[:sunpro][:version] = output[3]
-        c[:sunpro][:description] = so.stderr.chomp
+        @c[:sunpro] = Mash.new
+        @c[:sunpro][:version] = output[3]
+        @c[:sunpro][:description] = so.stderr.chomp
       end
     end
+  end
 
-    #hpux cc
+  def collect_hpux_cc
+    # hpux cc
     collect("what /opt/ansic/bin/cc") do |so|
       description = so.stdout.split($/).select { |line| line =~ /HP C Compiler/ }.first
       if description
         output = description.split
-        c[:hpcc] = Mash.new
-        c[:hpcc][:version] = output[1] if output.size >= 1
-        c[:hpcc][:description] = description.strip
+        @c[:hpcc] = Mash.new
+        @c[:hpcc][:version] = output[1] if output.size >= 1
+        @c[:hpcc][:description] = description.strip
       end
     end
+  end
+
+  collect_data(:aix) do
+    @c = Mash.new
+    collect_xlc
+    collect_gcc
+    languages[:c] = @c unless @c.empty?
+  end
+
+  collect_data(:darwin) do
+    @c = Mash.new
+    collect_gcc if xcode_installed?
+    languages[:c] = @c unless @c.empty?
+  end
+
+  collect_data(:windows) do
+    @c = Mash.new
+    check_for_cl
+    check_for_devenv
+    languages[:c] = @c unless @c.empty?
+  end
+
+  collect_data(:hpux) do
+    @c = Mash.new
+    collect_gcc
+    collect_hpux_cc
+    languages[:c] = @c unless @c.empty?
+  end
 
-    languages[:c] = c unless c.empty?
+  collect_data(:default) do
+    @c = Mash.new
+    collect_gcc
+    collect_glibc
+    collect_sunpro
+    languages[:c] = @c unless @c.empty?
   end
 end
diff --git a/spec/unit/plugins/c_spec.rb b/spec/unit/plugins/c_spec.rb
index 322d396f6..ca963f3c3 100644
--- a/spec/unit/plugins/c_spec.rb
+++ b/spec/unit/plugins/c_spec.rb
@@ -16,41 +16,19 @@
 # limitations under the License.
 #
 
-require "rbconfig"
-
 require File.expand_path(File.join(File.dirname(__FILE__), "..", "..", "/spec_helper.rb"))
 
 C_GCC = <<EOF
-Reading specs from /usr/lib/gcc/x86_64-redhat-linux/3.4.6/specs
-Configured with: ../configure --prefix=/usr ... --host=x86_64-redhat-linux
+Using built-in specs.
+COLLECT_GCC=gcc
+COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
+Target: x86_64-linux-gnu
+Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.4' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
 Thread model: posix
-gcc version 3.4.6 20060404 (Red Hat 3.4.6-3)
-EOF
-
-C_GLIBC_2_3_4 = <<EOF
-GNU C Library stable release version 2.3.4, by Roland McGrath et al.
-Copyright (C) 2005 Free Software Foundation, Inc.
-This is free software; see the source for copying conditions.
-There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
-PARTICULAR PURPOSE.
-Compiled by GNU CC version 3.4.6 20060404 (Red Hat 3.4.6-3).
-Compiled on a Linux 2.4.20 system on 2006-08-12.
-Available extensions:
-        GNU libio by Per Bothner
-        crypt add-on version 2.1 by Michael Glad and others
-        linuxthreads-0.10 by Xavier Leroy
-        The C stubs add-on version 2.1.2.
-        BIND-8.2.3-T5B
-        NIS(YP)/NIS+ NSS modules 0.19 by Thorsten Kukuk
-        Glibc-2.0 compatibility add-on by Cristian Gafton
-        GNU Libidn by Simon Josefsson
-        libthread_db work sponsored by Alpha Processor Inc
-Thread-local storage support included.
-For bug reporting instructions, please see:
-<http://www.gnu.org/software/libc/bugs.html>.
+gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4)
 EOF
 
-C_GLIBC_2_5 = <<EOF
+C_GLIBC = <<EOF
 GNU C Library stable release version 2.5, by Roland McGrath et al.
 Copyright (C) 2006 Free Software Foundation, Inc.
 This is free software; see the source for copying conditions.
@@ -109,251 +87,306 @@
     plugin[:languages] = Mash.new
     #gcc
     allow(plugin).to receive(:shell_out).with("gcc -v").and_return(mock_shell_out(0, "", C_GCC))
-    #glibc
-    allow(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_return(mock_shell_out(0, C_GLIBC_2_3_4, ""))
-    #ms cl
-    allow(plugin).to receive(:shell_out).with("cl /\?").and_return(mock_shell_out(0, "", C_CL))
-    #ms vs
-    allow(plugin).to receive(:shell_out).with("devenv.com /\?").and_return(mock_shell_out(0, C_VS, ""))
-    #ibm xlc
-    allow(plugin).to receive(:shell_out).with("xlc -qversion").and_return(mock_shell_out(0, C_XLC, ""))
-    #sun pro
-    allow(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(0, "", C_SUN))
-    #hpux cc
-    allow(plugin).to receive(:shell_out).with("what /opt/ansic/bin/cc").and_return(mock_shell_out(0, C_HPUX, ""))
-  end
-
-  #gcc
-  it "gets the gcc version from running gcc -v" do
-    expect(plugin).to receive(:shell_out).with("gcc -v").and_return(mock_shell_out(0, "", C_GCC))
-    plugin.run
-  end
-
-  it "sets languages[:c][:gcc][:version]" do
-    plugin.run
-    expect(plugin.languages[:c][:gcc][:version]).to eql("3.4.6")
-  end
-
-  it "sets languages[:c][:gcc][:description]" do
-    plugin.run
-    expect(plugin.languages[:c][:gcc][:description]).to eql(C_GCC.split($/).last)
-  end
-
-  it "does not set the languages[:c][:gcc] tree up if gcc command exits nonzero" do
-    allow(plugin).to receive(:shell_out).with("gcc -v").and_return(mock_shell_out(1, "", ""))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:gcc)
-  end
-
-  it "does not set the languages[:c][:gcc] tree up if gcc command fails" do
-    allow(plugin).to receive(:shell_out).with("gcc -v").and_raise(Ohai::Exceptions::Exec)
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:gcc)
-    expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
-  end
-
-  #glibc
-  it "gets the glibc x.x.x version from running /lib/libc.so.6", :unix_only do
-    expect(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_return(mock_shell_out(0, C_GLIBC_2_3_4, ""))
-    plugin.run
-  end
-
-  it "sets languages[:c][:glibc][:version]", :unix_only do
-    plugin.run
-    expect(plugin.languages[:c][:glibc][:version]).to eql("2.3.4")
-  end
-
-  it "sets languages[:c][:glibc][:description]", :unix_only do
-    plugin.run
-    expect(plugin.languages[:c][:glibc][:description]).to eql(C_GLIBC_2_3_4.split($/).first)
-  end
-
-  it "does not set the languages[:c][:glibc] tree up if glibc exits nonzero" do
-    allow(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_return(mock_shell_out(1, "", ""))
-    allow(plugin).to receive(:shell_out).with("/lib64/libc.so.6").and_return(mock_shell_out(1, "", ""))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:glibc)
-  end
-
-  it "does not set the languages[:c][:glibc] tree up if glibc fails" do
-    allow(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_raise(Ohai::Exceptions::Exec)
-    allow(plugin).to receive(:shell_out).with("/lib64/libc.so.6").and_raise(Ohai::Exceptions::Exec)
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:glibc)
-    expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
-  end
-
-  it "gets the glibc x.x version from running /lib/libc.so.6", :unix_only do
-    allow(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_return(mock_shell_out(0, C_GLIBC_2_5, ""))
-    expect(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_return(mock_shell_out(0, C_GLIBC_2_5, ""))
-    plugin.run
-    expect(plugin.languages[:c][:glibc][:version]).to eql("2.5")
-  end
-
-  #ms cl
-  it "gets the cl version from running cl /?" do
-    expect(plugin).to receive(:shell_out).with("cl /\?").and_return(mock_shell_out(0, "", C_CL))
-    plugin.run
-  end
-
-  it "sets languages[:c][:cl][:version]" do
-    plugin.run
-    expect(plugin.languages[:c][:cl][:version]).to eql("14.00.50727.762")
-  end
-
-  it "sets languages[:c][:cl][:description]" do
-    plugin.run
-    expect(plugin.languages[:c][:cl][:description]).to eql(C_CL.split($/).first)
-  end
-
-  it "does not set the languages[:c][:cl] tree up if cl command exits nonzero" do
-    allow(plugin).to receive(:shell_out).with("cl /\?").and_return(mock_shell_out(1, "", ""))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:cl)
-  end
-
-  it "does not set the languages[:c][:cl] tree up if cl command fails" do
-    allow(plugin).to receive(:shell_out).with("cl /\?").and_raise(Ohai::Exceptions::Exec)
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:cl)
-    expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
-  end
-
-  #ms vs
-  it "gets the vs version from running devenv.com /?" do
-    expect(plugin).to receive(:shell_out).with("devenv.com /\?").and_return(mock_shell_out(0, C_VS, ""))
-    plugin.run
-  end
-
-  it "sets languages[:c][:vs][:version]" do
-    plugin.run
-    expect(plugin.languages[:c][:vs][:version]).to eql("8.0.50727.762")
-  end
-
-  it "sets languages[:c][:vs][:description]" do
-    plugin.run
-    expect(plugin.languages[:c][:vs][:description]).to eql(C_VS.split($/)[1])
-  end
-
-  it "does not set the languages[:c][:vs] tree up if devenv command exits nonzero" do
-    allow(plugin).to receive(:shell_out).with("devenv.com /\?").and_return(mock_shell_out(1, "", ""))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:vs)
-  end
-
-  it "does not set the languages[:c][:vs] tree up if devenv command fails" do
-    allow(plugin).to receive(:shell_out).with("devenv.com /\?").and_raise(Ohai::Exceptions::Exec)
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:vs)
-    expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
-  end
-
-  #ibm xlc
-  it "gets the xlc version from running xlc -qversion" do
-    expect(plugin).to receive(:shell_out).with("xlc -qversion").and_return(mock_shell_out(0, C_XLC, ""))
-    plugin.run
-  end
-
-  it "sets languages[:c][:xlc][:version]" do
-    plugin.run
-    expect(plugin.languages[:c][:xlc][:version]).to eql("9.0")
-  end
-
-  it "sets languages[:c][:xlc][:description]" do
-    plugin.run
-    expect(plugin.languages[:c][:xlc][:description]).to eql(C_XLC.split($/).first)
-  end
-
-  it "does not set the languages[:c][:xlc] tree up if xlc command exits nonzero" do
-    allow(plugin).to receive(:shell_out).with("xlc -qversion").and_return(mock_shell_out(1, "", ""))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:xlc)
-  end
-
-  it "does not set the languages[:c][:xlc] tree up if xlc command fails" do
-    allow(plugin).to receive(:shell_out).with("xlc -qversion").and_raise(Ohai::Exceptions::Exec)
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:xlc)
-    expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
   end
 
-  it "sets the languages[:c][:xlc] tree up if xlc exit status is 249" do
-    allow(plugin).to receive(:shell_out).with("xlc -qversion").and_return(mock_shell_out(63744, "", ""))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:xlc)
-  end
-
-  #sun pro
-  it "gets the cc version from running cc -V -flags" do
-    expect(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(0, "", C_SUN))
-    plugin.run
-  end
+  context "on AIX" do
+    before(:each) do
+      allow(plugin).to receive(:collect_os).and_return(:aix)
+      allow(plugin).to receive(:shell_out).with("xlc -qversion").and_return(mock_shell_out(0, C_XLC, ""))
+    end
 
-  it "sets languages[:c][:sunpro][:version]" do
-    plugin.run
-    expect(plugin.languages[:c][:sunpro][:version]).to eql("5.8")
-  end
-
-  it "sets languages[:c][:sunpro][:description]" do
-    plugin.run
-    expect(plugin.languages[:c][:sunpro][:description]).to eql(C_SUN.chomp)
-  end
-
-  it "does not set the languages[:c][:sunpro] tree up if cc command exits nonzero" do
-    allow(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(1, "", ""))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:sunpro)
-  end
-
-  it "does not set the languages[:c][:sunpro] tree up if cc command fails" do
-    allow(plugin).to receive(:shell_out).with("cc -V -flags").and_raise(Ohai::Exceptions::Exec)
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:sunpro)
-    expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
-  end
-
-  it "does not set the languages[:c][:sunpro] tree if the corresponding cc command fails on linux" do
-    fedora_error_message = "cc: error trying to exec 'i686-redhat-linux-gcc--flags': execvp: No such file or directory"
-
-    allow(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(0, "", fedora_error_message))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:sunpro)
-  end
+    #ibm xlc
+    it "gets the xlc version from running xlc -qversion" do
+      expect(plugin).to receive(:shell_out).with("xlc -qversion").and_return(mock_shell_out(0, C_XLC, ""))
+      plugin.run
+    end
+
+    it "sets languages[:c][:xlc][:version]" do
+      plugin.run
+      expect(plugin.languages[:c][:xlc][:version]).to eql("9.0")
+    end
+
+    it "sets languages[:c][:xlc][:description]" do
+      plugin.run
+      expect(plugin.languages[:c][:xlc][:description]).to eql("IBM XL C/C++ Enterprise Edition for AIX, V9.0")
+    end
+
+    it "does not set the languages[:c][:xlc] tree up if xlc command exits nonzero" do
+      allow(plugin).to receive(:shell_out).with("xlc -qversion").and_return(mock_shell_out(1, "", ""))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:xlc)
+    end
+
+    it "does not set the languages[:c][:xlc] tree up if xlc command fails" do
+      allow(plugin).to receive(:shell_out).with("xlc -qversion").and_raise(Ohai::Exceptions::Exec)
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:xlc)
+      expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
+    end
+
+    it "sets the languages[:c][:xlc] tree up if xlc exit status is 249" do
+      allow(plugin).to receive(:shell_out).with("xlc -qversion").and_return(mock_shell_out(63744, "", ""))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:xlc)
+    end
+
+  end
+
+  context "on HPUX" do
+    before(:each) do
+      allow(plugin).to receive(:collect_os).and_return(:hpux)
+      allow(plugin).to receive(:shell_out).with("what /opt/ansic/bin/cc").and_return(mock_shell_out(0, C_HPUX, ""))
+    end
 
-  it "does not set the languages[:c][:sunpro] tree if the corresponding cc command fails on hpux" do
-    hpux_error_message = "cc: warning 901: unknown option: `-flags': use +help for online documentation.\ncc: HP C/aC++ B3910B A.06.25 [Nov 30 2009]"
-    allow(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(0, "", hpux_error_message))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:sunpro)
-  end
+    #hpux cc
+    it "gets the cc version from running what cc" do
+      expect(plugin).to receive(:shell_out).with("what /opt/ansic/bin/cc").and_return(mock_shell_out(0, C_HPUX, ""))
+      plugin.run
+    end
+
+    it "sets languages[:c][:hpcc][:version]" do
+      plugin.run
+      expect(plugin.languages[:c][:hpcc][:version]).to eql("B.11.11.16")
+    end
+
+    it "sets languages[:c][:hpcc][:description]" do
+      plugin.run
+      expect(plugin.languages[:c][:hpcc][:description]).to eql("HP92453-01 B.11.11.16 HP C Compiler")
+    end
+
+    it "does not set the languages[:c][:hpcc] tree up if cc command exits nonzero" do
+      allow(plugin).to receive(:shell_out).with("what /opt/ansic/bin/cc").and_return(mock_shell_out(1, "", ""))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:hpcc)
+    end
+
+    it "does not set the languages[:c][:hpcc] tree up if cc command fails" do
+      allow(plugin).to receive(:shell_out).with("what /opt/ansic/bin/cc").and_raise(Ohai::Exceptions::Exec)
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:hpcc)
+      expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
+    end
+  end
+
+  context "on Darwin" do
+    before(:each) do
+      allow(plugin).to receive(:shell_out).with("/usr/bin/xcode-select -p").and_return(mock_shell_out(0, "", ""))
+      allow(plugin).to receive(:collect_os).and_return(:darwin)
+    end
+
+    it "shells out to see if xcode is installed" do
+      expect(plugin).to receive(:shell_out).with("/usr/bin/xcode-select -p")
+      plugin.run
+    end
+
+    it "doesnt shellout to gcc if xcode isn't installed" do
+      allow(plugin).to receive(:shell_out).with("/usr/bin/xcode-select -p").and_return(mock_shell_out(1, "", ""))
+      expect(plugin).not_to receive(:shell_out).with("gcc -v")
+      plugin.run
+    end
+
+  end
+
+  context "on Windows" do
+    before(:each) do
+      allow(plugin).to receive(:collect_os).and_return(:windows)
+      allow(plugin).to receive(:shell_out).with("cl /\?").and_return(mock_shell_out(0, "", C_CL))
+      allow(plugin).to receive(:shell_out).with("devenv.com /\?").and_return(mock_shell_out(0, C_VS, ""))
+    end
 
-  #hpux cc
-  it "gets the cc version from running what cc" do
-    expect(plugin).to receive(:shell_out).with("what /opt/ansic/bin/cc").and_return(mock_shell_out(0, C_HPUX, ""))
-    plugin.run
-  end
+    #ms cl
+    it "gets the cl version from running cl /?" do
+      expect(plugin).to receive(:shell_out).with("cl /\?")
+      plugin.run
+    end
+
+    it "sets languages[:c][:cl][:version]" do
+      plugin.run
+      expect(plugin.languages[:c][:cl][:version]).to eql("14.00.50727.762")
+    end
+
+    it "sets languages[:c][:cl][:description]" do
+      plugin.run
+      expect(plugin.languages[:c][:cl][:description]).to eql("Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.762 for 80x86")
+    end
+
+    it "does not set the languages[:c][:cl] tree up if cl command exits nonzero" do
+      allow(plugin).to receive(:shell_out).with("cl /\?").and_return(mock_shell_out(1, "", ""))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:cl)
+    end
+
+    it "does not set the languages[:c][:cl] tree up if cl command fails" do
+      allow(plugin).to receive(:shell_out).with("cl /\?").and_raise(Ohai::Exceptions::Exec)
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:cl)
+      expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
+    end
 
-  it "sets languages[:c][:hpcc][:version]" do
-    plugin.run
-    expect(plugin.languages[:c][:hpcc][:version]).to eql("B.11.11.16")
-  end
+    #ms vs
+    it "gets the vs version from running devenv.com /?" do
+      expect(plugin).to receive(:shell_out).with("devenv.com /\?").and_return(mock_shell_out(0, C_VS, ""))
+      plugin.run
+    end
+
+    it "sets languages[:c][:vs][:version]" do
+      plugin.run
+      expect(plugin.languages[:c][:vs][:version]).to eql("8.0.50727.762")
+    end
+
+    it "sets languages[:c][:vs][:description]" do
+      plugin.run
+      expect(plugin.languages[:c][:vs][:description]).to eql("Microsoft (R) Visual Studio Version 8.0.50727.762.")
+    end
+
+    it "does not set the languages[:c][:vs] tree up if devenv command exits nonzero" do
+      allow(plugin).to receive(:shell_out).with("devenv.com /\?").and_return(mock_shell_out(1, "", ""))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:vs)
+    end
+
+    it "does not set the languages[:c][:vs] tree up if devenv command fails" do
+      allow(plugin).to receive(:shell_out).with("devenv.com /\?").and_raise(Ohai::Exceptions::Exec)
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:vs)
+      expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
+    end
+  end
+
+  context "on Linux" do
+    before(:each) do
+      allow(plugin).to receive(:collect_os).and_return(:linux)
+      # glibc
+      allow(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_return(mock_shell_out(0, C_GLIBC, ""))
+      allow(plugin).to receive(:shell_out).with("/lib64/libc.so.6").and_return(mock_shell_out(0, C_GLIBC, ""))
+      #sun pro
+      allow(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(0, "", C_SUN))
+    end
 
-  it "sets languages[:c][:hpcc][:description]" do
-    plugin.run
-    expect(plugin.languages[:c][:hpcc][:description]).to eql(C_HPUX.split($/)[3].strip)
-  end
+    #gcc
+    it "gets the gcc version from running gcc -v" do
+      expect(plugin).to receive(:shell_out).with("gcc -v")
+      plugin.run
+    end
+
+    it "sets languages[:c][:gcc][:version]" do
+      plugin.run
+      expect(plugin.languages[:c][:gcc][:version]).to eql("5.4.0")
+    end
+
+    it "sets languages[:c][:gcc][:description]" do
+      plugin.run
+      expect(plugin.languages[:c][:gcc][:description]).to eql("gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4)")
+    end
+
+    it "sets languages[:c][:gcc][:configured_with]" do
+      plugin.run
+      expect(plugin.languages[:c][:gcc][:configured_with]).to eql("../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.4' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu")
+    end
+
+    it "sets languages[:c][:gcc][:target]" do
+      plugin.run
+      expect(plugin.languages[:c][:gcc][:target]).to eql("x86_64-linux-gnu")
+    end
+
+    it "sets languages[:c][:gcc][:thread_model]" do
+      plugin.run
+      expect(plugin.languages[:c][:gcc][:thread_model]).to eql("posix")
+    end
+
+    it "does not set the languages[:c][:gcc] tree up if gcc command exits nonzero" do
+      allow(plugin).to receive(:shell_out).with("gcc -v").and_return(mock_shell_out(1, "", ""))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:gcc)
+    end
+
+    it "does not set the languages[:c][:gcc] tree up if gcc command fails" do
+      allow(plugin).to receive(:shell_out).with("gcc -v").and_raise(Ohai::Exceptions::Exec)
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:gcc)
+      expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
+    end
 
-  it "does not set the languages[:c][:hpcc] tree up if cc command exits nonzero" do
-    allow(plugin).to receive(:shell_out).with("what /opt/ansic/bin/cc").and_return(mock_shell_out(1, "", ""))
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:hpcc)
-  end
+    #glibc
+    it "gets the glibc x.x.x version from running /lib/libc.so.6" do
+      expect(plugin).to receive(:shell_out).with("/lib/libc.so.6")
+      plugin.run
+    end
+
+    it "sets languages[:c][:glibc][:version]", :unix_only do
+      plugin.run
+      expect(plugin.languages[:c][:glibc][:version]).to eql("2.5")
+    end
+
+    it "sets languages[:c][:glibc][:description]" do
+      plugin.run
+      expect(plugin.languages[:c][:glibc][:description]).to eql("GNU C Library stable release version 2.5, by Roland McGrath et al.")
+    end
+
+    it "does not set the languages[:c][:glibc] tree up if glibc exits nonzero" do
+      allow(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_return(mock_shell_out(1, "", ""))
+      allow(plugin).to receive(:shell_out).with("/lib64/libc.so.6").and_return(mock_shell_out(1, "", ""))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:glibc)
+    end
+
+    it "does not set the languages[:c][:glibc] tree up if glibc fails" do
+      allow(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_raise(Ohai::Exceptions::Exec)
+      allow(plugin).to receive(:shell_out).with("/lib64/libc.so.6").and_raise(Ohai::Exceptions::Exec)
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:glibc)
+      expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
+    end
+
+    it "gets the glibc x.x version from running /lib/libc.so.6" do
+      allow(plugin).to receive(:shell_out).with("/lib/libc.so.6").and_return(mock_shell_out(0, C_GLIBC, ""))
+      expect(plugin).to receive(:shell_out).with("/lib/libc.so.6")
+      plugin.run
+      expect(plugin.languages[:c][:glibc][:version]).to eql("2.5")
+    end
 
-  it "does not set the languages[:c][:hpcc] tree up if cc command fails" do
-    allow(plugin).to receive(:shell_out).with("what /opt/ansic/bin/cc").and_raise(Ohai::Exceptions::Exec)
-    plugin.run
-    expect(plugin[:languages][:c]).not_to have_key(:hpcc)
-    expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
+    #sun pro
+    it "gets the cc version from running cc -V -flags" do
+      expect(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(0, "", C_SUN))
+      plugin.run
+    end
+
+    it "sets languages[:c][:sunpro][:version]" do
+      plugin.run
+      expect(plugin.languages[:c][:sunpro][:version]).to eql("5.8")
+    end
+
+    it "sets languages[:c][:sunpro][:description]" do
+      plugin.run
+      expect(plugin.languages[:c][:sunpro][:description]).to eql("cc: Sun C 5.8 Patch 121016-06 2007/08/01")
+    end
+
+    it "does not set the languages[:c][:sunpro] tree up if cc command exits nonzero" do
+      allow(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(1, "", ""))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:sunpro)
+    end
+
+    it "does not set the languages[:c][:sunpro] tree up if cc command fails" do
+      allow(plugin).to receive(:shell_out).with("cc -V -flags").and_raise(Ohai::Exceptions::Exec)
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:sunpro)
+      expect(plugin[:languages][:c]).not_to be_empty # expect other attributes
+    end
+
+    it "does not set the languages[:c][:sunpro] tree if the corresponding cc command fails on linux" do
+      fedora_error_message = "cc: error trying to exec 'i686-redhat-linux-gcc--flags': execvp: No such file or directory"
+
+      allow(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(0, "", fedora_error_message))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:sunpro)
+    end
+
+    it "does not set the languages[:c][:sunpro] tree if the corresponding cc command fails on hpux" do
+      hpux_error_message = "cc: warning 901: unknown option: `-flags': use +help for online documentation.\ncc: HP C/aC++ B3910B A.06.25 [Nov 30 2009]"
+      allow(plugin).to receive(:shell_out).with("cc -V -flags").and_return(mock_shell_out(0, "", hpux_error_message))
+      plugin.run
+      expect(plugin[:languages][:c]).not_to have_key(:sunpro)
+    end
   end
-
 end