Homebrew::EnvConfig: add tests.

Library/Homebrew/test/.rubocop_todo.yml

@@ -30,6 +30,7 @@ RSpec/FilePath:
     - 'checksum_verification_spec.rb'
     - 'cxxstdlib_spec.rb'
     - 'diagnostic_checks_spec.rb'
+    - 'env_config_spec.rb'
     - 'missing_formula_spec.rb'
     - 'os/linux/diagnostic_spec.rb'
     - 'os/mac/diagnostic_spec.rb'

Library/Homebrew/test/env_config_spec.rb

+# frozen_string_literal: true
+
+require "diagnostic"
+
+describe Homebrew::EnvConfig do
+  subject(:env_config) { described_class }
+
+  describe ".env_method_name" do
+    it "generates method names" do
+      expect(env_config.env_method_name("HOMEBREW_FOO", {})).to eql("foo")
+    end
+
+    it "generates boolean method names" do
+      expect(env_config.env_method_name("HOMEBREW_BAR", boolean: true)).to eql("bar?")
+    end
+  end
+
+  describe ".artifact_domain" do
+    it "returns value if set" do
+      ENV["HOMEBREW_ARTIFACT_DOMAIN"] = "https://brew.sh"
+      expect(env_config.artifact_domain).to eql("https://brew.sh")
+    end
+
+    it "returns nil if empty" do
+      ENV["HOMEBREW_ARTIFACT_DOMAIN"] = ""
+      expect(env_config.artifact_domain).to be_nil
+    end
+  end
+
+  describe ".auto_update_secs" do
+    it "returns value if set" do
+      ENV["HOMEBREW_AUTO_UPDATE_SECS"] = "360"
+      expect(env_config.auto_update_secs).to eql("360")
+    end
+
+    it "returns default if unset" do
+      ENV["HOMEBREW_AUTO_UPDATE_SECS"] = nil
+      expect(env_config.auto_update_secs).to eql("300")
+    end
+  end
+
+  describe ".bat?" do
+    it "returns true if set" do
+      ENV["HOMEBREW_BAT"] = "1"
+      expect(env_config.bat?).to be(true)
+    end
+
+    it "returns false if unset" do
+      ENV["HOMEBREW_BAT"] = nil
+      expect(env_config.bat?).to be(false)
+    end
+  end
+
+  describe ".make_jobs" do
+    it "returns value if positive" do
+      ENV["HOMEBREW_MAKE_JOBS"] = "4"
+      expect(env_config.make_jobs).to eql("4")
+    end
+
+    it "returns default if negative" do
+      ENV["HOMEBREW_MAKE_JOBS"] = "-1"
+      expect(Hardware::CPU).to receive(:cores).and_return(16)
+      expect(env_config.make_jobs).to eql("16")
+    end
+  end
+end