Do not crash when loading undefined context from hash

When loading `from_hash` and with `strict_mode false`,
a config context that is not defined will cause
mixlib-config to crash.

This is because we used `internal_get` without checking
to see if the result was nil.  nil occurs when the
scenario above is met.  Now, we will define the context
when this happens, and continue to populate that context
from the hash.

Signed-off-by: Marc A. Paradise <marc.paradise@gmail.com>

2 files changed, 41 insertions, 21 deletions

diff --git a/lib/mixlib/config.rb b/lib/mixlib/config.rb
index 9937182..00385da 100644
--- a/lib/mixlib/config.rb
+++ b/lib/mixlib/config.rb
@@ -569,7 +569,10 @@ module Mixlib
     def apply_nested_hash(hash)
       hash.each do |k, v|
         if v.is_a? Hash
-          internal_get(k.to_sym).apply_nested_hash(v)
+          # If loading from hash, and we reference a context that doesn't exist
+          # and warning/strict is off, we need to create the config context that we expected to be here.
+          context = internal_get(k.to_sym) || config_context(k.to_sym)
+          context.apply_nested_hash(v)
         else
           internal_set(k.to_sym, v)
         end
diff --git a/spec/mixlib/config_spec.rb b/spec/mixlib/config_spec.rb
index de4147b..1155e75 100644
--- a/spec/mixlib/config_spec.rb
+++ b/spec/mixlib/config_spec.rb
@@ -1274,28 +1274,45 @@ describe Mixlib::Config do
   end
 
   describe ".from_hash" do
-    let(:hash) do
-      {
-        "alpha" => "beta",
-        gamma: "delta",
-        "foo" => %w{ bar baz matazz},
-        "bar" => { "baz" => { "fizz" => "buzz" } },
-        "windows_path" => 'C:\Windows Has Awful\Paths',
-      }
-    end
-
-    it "configures the config object from a hash" do
-      ConfigIt.config_context :bar do
-        config_context :baz do
-          default :fizz, "quux"
+    context "when contexts in the hash are defined" do
+      let(:hash) do
+        {
+          "alpha" => "beta",
+          gamma: "delta",
+          "foo" => %w{ bar baz matazz},
+          "bar" => { "baz" => { "fizz" => "buzz" } },
+          "windows_path" => 'C:\Windows Has Awful\Paths',
+        }
+      end
+      it "configures the config object from a hash" do
+        ConfigIt.config_context :bar do
+          config_context :baz do
+            default :fizz, "quux"
+          end
         end
+        ConfigIt.from_hash(hash)
+        expect(ConfigIt.foo).to eql(%w{ bar baz matazz })
+        expect(ConfigIt.alpha).to eql("beta")
+        expect(ConfigIt.gamma).to eql("delta")
+        expect(ConfigIt[:bar][:baz][:fizz]).to eql("buzz")
+        expect(ConfigIt.windows_path).to eql('C:\Windows Has Awful\Paths')
+      end
+    end
+    context "when contexts in the hash are undefined and strict disabled" do
+      before do
+        ConfigIt.strict_mode = true
+      end
+      let(:hash) do
+        {
+          "brrr" => { "baz" => { "fizz" => "buzz" } },
+          "windows_path" => 'C:\Windows Has Awful\Paths',
+        }
+      end
+      it "configures the config object, creating contexts as needed" do
+        ConfigIt.from_hash(hash)
+        expect(ConfigIt[:brrr][:baz][:fizz]).to eql("buzz")
+        expect(ConfigIt.windows_path).to eql('C:\Windows Has Awful\Paths')
       end
-      ConfigIt.from_hash(hash)
-      expect(ConfigIt.foo).to eql(%w{ bar baz matazz })
-      expect(ConfigIt.alpha).to eql("beta")
-      expect(ConfigIt.gamma).to eql("delta")
-      expect(ConfigIt[:bar][:baz][:fizz]).to eql("buzz")
-      expect(ConfigIt.windows_path).to eql('C:\Windows Has Awful\Paths')
     end
   end
 end