coverage data tests 💃

spec/coverage_data_spec.rb

@@ -0,0 +1,74 @@
+# frozen_string_literal: true
+
+require "helper"
+
+RSpec.describe SimpleCov::CoverageData do
+  describe ".new" do
+    it "retains statistics and computes new ones" do
+      data = described_class.new(covered: 4, missed: 6, total_strength: 14)
+
+      expect(data.covered).to eq 4
+      expect(data.missed).to eq 6
+
+      expect(data.total).to eq 10
+      expect(data.percent).to eq 40.0
+      expect(data.strength).to eq 1.4
+    end
+
+    it "can omit the total strength defaulting to 0.0" do
+      data = described_class.new(covered: 4, missed: 6, total_strength: 0.0)
+
+      expect(data.strength).to eq 0.0
+    end
+
+    it "can deal with it if everything is 0" do
+      data = described_class.new(covered: 0, missed: 0, total_strength: 0.0)
+
+      expect_all_empty(data)
+    end
+  end
+
+  describe ".from" do
+    it "returns an all 0s coverage data if there is no data" do
+      data = described_class.from([])
+
+      expect_all_empty(data)
+    end
+
+    it "returns all empty data when initialized with a couple of empty results" do
+      data = described_class.from([empty_data, empty_data])
+
+      expect_all_empty(data)
+    end
+
+    it "produces sensible total results" do
+      data = described_class.from(
+        [
+          described_class.new(covered: 3, missed: 4, total_strength: 54),
+          described_class.new(covered: 0, missed: 13, total_strength: 0),
+          described_class.new(covered: 37, missed: 0, total_strength: 682)
+        ]
+      )
+
+      expect(data.covered).to eq 40
+      expect(data.missed).to eq 17
+      expect(data.total).to eq 57
+      expect(data.percent).to be_within(0.01).of(70.18)
+      expect(data.strength).to be_within(0.01).of(12.91)
+    end
+  end
+
+  def empty_data
+    described_class.new(covered: 0, missed: 0, total_strength: 0.0)
+  end
+
+  def expect_all_empty(data)
+    expect(data.covered).to eq 0
+    expect(data.missed).to eq 0
+
+    expect(data.total).to eq 0
+    # might be counter intuitive but think of it as "we covered everything we could"
+    expect(data.percent).to eq 100.0
+    expect(data.strength).to eq 0.0
+  end
+end