Writing some (failing) tests for instrumentation

test/test_instrumentation.rb

@@ -0,0 +1,43 @@
+require_relative "./helper"
+
+class TestInstrumentation < Minitest::Test
+  include Linguist
+
+  class LocalInstrumenter
+    Event = Struct.new(:name, :args)
+
+    attr_reader :events
+
+    def initialize
+      @events = []
+    end
+
+    def instrument(name, *args)
+      @events << Event.new(name, args)
+    end
+  end
+
+  def setup
+    Linguist.instrumenter = LocalInstrumenter.new
+  end
+
+  def teardown
+    Linguist.instrumenter = nil
+  end
+
+  def test_detection_instrumentation_with_binary_blob
+    binary_blob = fixture_blob("Binary/octocat.ai")
+    Language.detect(binary_blob)
+
+    # Shouldn't instrument this (as it's binary)
+    assert_equal 0, Linguist.instrumenter.events.size
+  end
+
+  def test_modeline_instrumentation
+    blob = fixture_blob("Data/Modelines/ruby")
+    Language.detect(blob)
+
+    assert_equal 3, Linguist.instrumenter.events.size
+    assert_equal "linguist.detected", Linguist.instrumenter.events.last.name
+  end
+end