Add `File.absolute_path?` (#2198)

In order to check whether a path is absolute or not in a portable way.

[Feature #15868]

1 files changed, 53 insertions, 0 deletions

diff --git a/spec/ruby/core/file/absolute_path_spec.rb b/spec/ruby/core/file/absolute_path_spec.rb
index d6f3f060c7..52839cf1cc 100644
--- a/spec/ruby/core/file/absolute_path_spec.rb
+++ b/spec/ruby/core/file/absolute_path_spec.rb
@@ -1,5 +1,58 @@
 require_relative '../../spec_helper'
 
+ruby_version_is "2.7" do
+  describe "File.absolute_path?" do
+    before :each do
+      @abs = File.expand_path(__FILE__)
+    end
+
+    it "returns true if it's an absolute pathname" do
+      File.absolute_path?(@abs).should be_true
+    end
+
+    it "returns false if it's a relative path" do
+      File.absolute_path?(File.basename(__FILE__)).should be_false
+    end
+
+    it "returns false if it's a tricky relative path" do
+      File.absolute_path?("C:foo\\bar").should be_false
+    end
+
+    it "does not expand '~' to a home directory." do
+      File.absolute_path?('~').should be_false
+    end
+
+    it "does not expand '~user' to a home directory." do
+      path = File.dirname(@abs)
+      Dir.chdir(path) do
+        File.absolute_path?('~user').should be_false
+      end
+    end
+
+    it "calls #to_path on its argument" do
+      mock = mock_to_path(File.expand_path(__FILE__))
+
+      File.absolute_path?(mock).should be_true
+    end
+
+    platform_is_not :windows do
+      it "takes into consideration the platform's root" do
+        File.absolute_path?("C:\\foo\\bar").should be_false
+        File.absolute_path?("C:/foo/bar").should be_false
+        File.absolute_path?("/foo/bar\\baz").should be_true
+      end
+    end
+
+    platform_is :windows do
+      it "takes into consideration the platform path separator(s)" do
+        File.absolute_path?("C:\\foo\\bar").should be_true
+        File.absolute_path?("C:/foo/bar").should be_true
+        File.absolute_path?("/foo/bar\\baz").should be_false
+      end
+    end
+  end
+end
+
 describe "File.absolute_path" do
   before :each do
     @abs = File.expand_path(__FILE__)