diff --git a/lib/floe/workflow/reference_path.rb b/lib/floe/workflow/reference_path.rb
index 5650145a..2633c0fa 100644
--- a/lib/floe/workflow/reference_path.rb
+++ b/lib/floe/workflow/reference_path.rb
@@ -3,16 +3,6 @@
 module Floe
   class Workflow
     class ReferencePath < Path
-      class << self
-        def get(payload, context)
-          new(payload).get(context)
-        end
-
-        def set(payload, context, value)
-          new(payload).set(context, value)
-        end
-      end
-
       attr_reader :path
 
       def initialize(*)
diff --git a/lib/floe/workflow/states/task.rb b/lib/floe/workflow/states/task.rb
index 47c3e522..c0a7e626 100644
--- a/lib/floe/workflow/states/task.rb
+++ b/lib/floe/workflow/states/task.rb
@@ -142,10 +142,6 @@ def parse_output(output)
         rescue JSON::ParserError
           nil
         end
-
-        def next_state
-          end? ? nil : @next
-        end
       end
     end
   end
diff --git a/spec/floe_spec.rb b/spec/floe_spec.rb
new file mode 100644
index 00000000..5af6ea7c
--- /dev/null
+++ b/spec/floe_spec.rb
@@ -0,0 +1,13 @@
+RSpec.describe Floe do
+  describe "logger=", "logger" do
+    it "sets the logger" do
+      old_logger = Floe.logger
+      new_logger = "abc"
+
+      Floe.logger = new_logger
+      expect(Floe.logger).to eq(new_logger)
+
+      Floe.logger = old_logger
+    end
+  end
+end
diff --git a/spec/runner_spec.rb b/spec/runner_spec.rb
new file mode 100644
index 00000000..8b80e306
--- /dev/null
+++ b/spec/runner_spec.rb
@@ -0,0 +1,78 @@
+RSpec.describe Floe::Runner do
+  let(:runner) { described_class.new }
+
+  describe ".register_scheme", ".for_resource" do
+    it "registers a scheme" do
+      x = Class.new
+      y = Class.new
+
+      described_class.register_scheme("x", x)
+      described_class.register_scheme("y", y)
+
+      expect(described_class.for_resource("x://abc")).to eq(x)
+      expect(described_class.for_resource("y://abc")).to eq(y)
+    end
+
+    it "overrides a scheme" do
+      x = Class.new
+      x2 = Class.new
+
+      described_class.register_scheme("x", x)
+      described_class.register_scheme("x", x2)
+
+      expect(described_class.for_resource("x://abc")).to eq(x2)
+    end
+
+    it "resolves a scheme lambda" do
+      x = Class.new
+
+      described_class.register_scheme("x", -> { x })
+
+      expect(described_class.for_resource("x://abc")).to eq(x)
+    end
+  end
+
+  # interface methods (not implemented)
+
+  describe "#run_async!" do
+    it "is not implemented" do
+      expect { runner.run_async!("local://resource") }.to raise_error(NotImplementedError)
+    end
+  end
+
+  describe "#status!" do
+    it "is not implemented" do
+      expect { runner.status!({}) }.to raise_error(NotImplementedError)
+    end
+  end
+
+  describe "#running?" do
+    it "is not implemented" do
+      expect { runner.running?({}) }.to raise_error(NotImplementedError)
+    end
+  end
+
+  describe "#success?" do
+    it "is not implemented" do
+      expect { runner.success?({}) }.to raise_error(NotImplementedError)
+    end
+  end
+
+  describe "#output" do
+    it "is not implemented" do
+      expect { runner.output({}) }.to raise_error(NotImplementedError)
+    end
+  end
+
+  describe "#cleanup" do
+    it "is not implemented" do
+      expect { runner.cleanup({}) }.to raise_error(NotImplementedError)
+    end
+  end
+
+  describe "#wait" do
+    it "is not implemented" do
+      expect { runner.wait }.to raise_error(NotImplementedError)
+    end
+  end
+end
diff --git a/spec/workflow/choice_rule_spec.rb b/spec/workflow/choice_rule_spec.rb
index b08209ad..92e287f5 100644
--- a/spec/workflow/choice_rule_spec.rb
+++ b/spec/workflow/choice_rule_spec.rb
@@ -3,6 +3,14 @@
     let(:subject) { described_class.build(payload).true?(context, input) }
     let(:context) { {} }
 
+    context "Abstract Interface" do
+      let(:input) { {} }
+      let(:subject) { described_class.new({}).true?(context, input) }
+      it "is not implemented" do
+        expect { subject }.to raise_exception(NotImplementedError)
+      end
+    end
+
     context "Boolean Expression" do
       context "Not" do
         let(:payload) { {"Not" => {"Variable" => "$.foo", "StringEquals" => "bar"}, "Next" => "FirstMatchState"} }
diff --git a/spec/workflow/context_spec.rb b/spec/workflow/context_spec.rb
index 74753929..1111d6c1 100644
--- a/spec/workflow/context_spec.rb
+++ b/spec/workflow/context_spec.rb
@@ -78,6 +78,8 @@
 
     it "ended" do
       ctx.state["Output"] = input.dup
+      ctx.execution["StartTime"] ||= Time.now.utc
+      ctx.execution["EndTime"] ||= Time.now.utc
 
       expect(ctx.failed?).to eq(false)
     end
@@ -91,6 +93,34 @@
     end
   end
 
+  describe "#success?" do
+    it "new context" do
+      expect(ctx.success?).to eq(false)
+    end
+
+    it "started" do
+      ctx.state["Output"] = {}
+
+      expect(ctx.success?).to eq(false)
+    end
+
+    it "ended" do
+      ctx.state["Output"] = input.dup
+      ctx.execution["StartTime"] ||= Time.now.utc
+      ctx.execution["EndTime"] ||= Time.now.utc
+
+      expect(ctx.success?).to eq(true)
+    end
+
+    it "ended with error" do
+      ctx.execution["StartTime"] ||= Time.now.utc
+      ctx.execution["EndTime"] ||= Time.now.utc
+      ctx.output = {"Cause" => "issue", "Error" => "error"}
+
+      expect(ctx.success?).to eq(false)
+    end
+  end
+
   describe "#input" do
     it "started" do
       ctx.state["Input"] = input
diff --git a/spec/workflow/payload_template_spec.rb b/spec/workflow/payload_template_spec.rb
index 49197829..7b540509 100644
--- a/spec/workflow/payload_template_spec.rb
+++ b/spec/workflow/payload_template_spec.rb
@@ -2,12 +2,21 @@
   let(:subject) { described_class.new(payload) }
 
   describe "#value" do
+    context "with static array" do
+      let(:payload) { ["a", 2] }
+      let(:context) { {} }
+
+      it "returns the original value" do
+        expect(subject.value(context)).to eq(["a", 2])
+      end
+    end
+
     context "with static values" do
-      let(:payload) { {"foo" => "bar", "bar" => "$.baz"} }
+      let(:payload) { {"foo" => "bar", "bar" => "$.baz", "baz" => 3} }
       let(:context) { {} }
 
       it "returns the original value" do
-        expect(subject.value(context)).to eq({"foo" => "bar", "bar" => "$.baz"})
+        expect(subject.value(context)).to eq({"foo" => "bar", "bar" => "$.baz", "baz" => 3})
       end
     end
 
diff --git a/spec/workflow/state_spec.rb b/spec/workflow/state_spec.rb
new file mode 100644
index 00000000..d340d896
--- /dev/null
+++ b/spec/workflow/state_spec.rb
@@ -0,0 +1,45 @@
+RSpec.describe Floe::Workflow::State do
+  let(:input)    { {} }
+  let(:ctx)      { Floe::Workflow::Context.new(:input => input) }
+  let(:state)    { workflow.current_state }
+  # picked a state that doesn't instantly finish
+  let(:workflow) { make_workflow(ctx, {"WaitState" => {"Type" => "Wait", "Seconds" => 1, "Next" => "SuccessState"}, "SuccessState" => {"Type" => "Succeed"}}) }
+
+  describe "#started?" do
+    it "is not started yet" do
+      expect(state.started?).to eq(false)
+    end
+
+    it "is started" do
+      state.start(ctx.input)
+      expect(state.started?).to eq(true)
+    end
+
+    it "is finished" do
+      state.start(ctx.input)
+      state.finish
+
+      state.start(ctx.input)
+      expect(state.started?).to eq(true)
+    end
+  end
+
+  describe "#finished?" do
+    it "is not started yet" do
+      expect(state.finished?).to eq(false)
+    end
+
+    it "is started" do
+      state.start(ctx.input)
+      expect(state.finished?).to eq(false)
+    end
+
+    it "is finished" do
+      state.start(ctx.input)
+      state.finish
+
+      state.start(ctx.input)
+      expect(state.finished?).to eq(true)
+    end
+  end
+end
diff --git a/spec/workflow_spec.rb b/spec/workflow_spec.rb
index d69bc6cb..8c10bf06 100644
--- a/spec/workflow_spec.rb
+++ b/spec/workflow_spec.rb
@@ -34,6 +34,10 @@
       expect { described_class.new(payload) }.to raise_error(Floe::InvalidWorkflowError, "Missing field \"States\"")
     end
 
+    it "raises an exception for invalid States" do
+      expect { make_workflow(ctx, {"FirstState" => {"Type" => "Invalid"}}) }.to raise_error(Floe::InvalidWorkflowError, "Invalid state type: [Invalid]")
+    end
+
     it "raises an exception for missing StartAt" do
       payload = {"Comment" => "Test", "States" => {}}
 
@@ -58,6 +62,10 @@
 
       expect { described_class.new(payload) }.to raise_error(Floe::InvalidWorkflowError, /must be less than or equal to 80 characters/)
     end
+
+    it "raises an exception for invalid context" do
+      expect { described_class.new(make_payload({"Start" => {"Type" => "Success"}}), "abc") }.to raise_error(Floe::InvalidWorkflowError, /unexpected token/)
+    end
   end
 
   describe "#run_nonblock" do