test: add Utils::ShellCompletion specs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mvanhorn

Library/Homebrew/test/utils/shell_completion_spec.rb

@@ -0,0 +1,107 @@
+# frozen_string_literal: true
+
+require "utils/shell_completion"
+
+RSpec.describe Utils::ShellCompletion do
+  describe ".default_completion_shells" do
+    it "returns bash, zsh, and fish for nil format" do
+      expect(described_class.default_completion_shells(nil)).to eq([:bash, :zsh, :fish])
+    end
+
+    it "returns bash, zsh, and fish for unrecognized format" do
+      expect(described_class.default_completion_shells(:unknown)).to eq([:bash, :zsh, :fish])
+    end
+
+    it "includes pwsh for cobra format" do
+      expect(described_class.default_completion_shells(:cobra)).to eq([:bash, :zsh, :fish, :pwsh])
+    end
+
+    it "includes pwsh for typer format" do
+      expect(described_class.default_completion_shells(:typer)).to eq([:bash, :zsh, :fish, :pwsh])
+    end
+  end
+
+  describe ".completion_shell_parameter" do
+    let(:env) { {} }
+
+    it "returns shell name for nil format" do
+      expect(described_class.completion_shell_parameter(nil, :bash, "/usr/bin/foo", env)).to eq("bash")
+    end
+
+    it "returns --shell=<name> for :arg format" do
+      expect(described_class.completion_shell_parameter(:arg, :zsh, "/usr/bin/foo", env)).to eq("--shell=zsh")
+    end
+
+    it "sets env and returns nil for :clap format" do
+      result = described_class.completion_shell_parameter(:clap, :fish, "/usr/bin/foo", env)
+      expect(result).to be_nil
+      expect(env["COMPLETE"]).to eq("fish")
+    end
+
+    it "sets env with uppercased program name for :click format" do
+      result = described_class.completion_shell_parameter(:click, :bash, "/usr/local/bin/my-tool", env)
+      expect(result).to be_nil
+      expect(env["_MY_TOOL_COMPLETE"]).to eq("bash_source")
+    end
+
+    it "returns subcommand array for :cobra format" do
+      result = described_class.completion_shell_parameter(:cobra, :zsh, "/usr/bin/foo", env)
+      expect(result).to eq(["completion", "zsh"])
+    end
+
+    it "returns --<shell> for :flag format" do
+      expect(described_class.completion_shell_parameter(:flag, :fish, "/usr/bin/foo", env)).to eq("--fish")
+    end
+
+    it "returns nil for :none format" do
+      expect(described_class.completion_shell_parameter(:none, :bash, "/usr/bin/foo", env)).to be_nil
+    end
+
+    it "returns subcommand array for :typer format and sets env" do
+      result = described_class.completion_shell_parameter(:typer, :bash, "/usr/bin/foo", env)
+      expect(result).to eq(["--show-completion", "bash"])
+      expect(env["_TYPER_COMPLETE_TEST_DISABLE_SHELL_DETECTION"]).to eq("1")
+    end
+
+    it "maps :pwsh to 'powershell'" do
+      expect(described_class.completion_shell_parameter(nil, :pwsh, "/usr/bin/foo", env)).to eq("powershell")
+    end
+
+    it "interpolates custom format string" do
+      expect(described_class.completion_shell_parameter("--complete-", :zsh, "/usr/bin/foo", env))
+        .to eq("--complete-zsh")
+    end
+  end
+
+  describe ".generate_completion_output" do
+    it "calls safe_popen_read with commands and shell parameter" do
+      expect(Utils).to receive(:safe_popen_read).with(
+        {}, "/usr/bin/foo", "completions", "bash", err: :err
+      ).and_return("completion output")
+
+      result = described_class.generate_completion_output(
+        ["/usr/bin/foo", "completions"], "bash", {}
+      )
+
+      expect(result).to eq("completion output")
+    end
+
+    it "flattens array shell parameters" do
+      expect(Utils).to receive(:safe_popen_read).with(
+        {}, "/usr/bin/foo", "completion", "zsh", err: :err
+      ).and_return("output")
+
+      described_class.generate_completion_output(
+        ["/usr/bin/foo"], ["completion", "zsh"], {}
+      )
+    end
+
+    it "handles nil shell parameter" do
+      expect(Utils).to receive(:safe_popen_read).with(
+        {}, "/usr/bin/foo", err: :err
+      ).and_return("output")
+
+      described_class.generate_completion_output(["/usr/bin/foo"], nil, {})
+    end
+  end
+end