Fix docs generator when git executable is missing

spec/compiler/crystal/tools/doc/project_info_spec.cr

@@ -33,7 +33,17 @@ describe Crystal::Doc::ProjectInfo do
         File.write("shard.yml", "name: foo\nversion: 1.0")
       end
 
-      it "no git" do
+      it "git missing" do
+        ProjectInfo.git_executable = "git-missing-executable"
+
+        assert_with_defaults(ProjectInfo.new(nil, nil), ProjectInfo.new("foo", "1.0", refname: nil))
+        assert_with_defaults(ProjectInfo.new("bar", "2.0"), ProjectInfo.new("bar", "2.0", refname: nil))
+        assert_with_defaults(ProjectInfo.new(nil, "2.0"), ProjectInfo.new("foo", "2.0", refname: nil))
+      ensure
+        ProjectInfo.git_executable = "git"
+      end
+
+      it "not in a git folder" do
         assert_with_defaults(ProjectInfo.new(nil, nil), ProjectInfo.new("foo", "1.0", refname: nil))
         assert_with_defaults(ProjectInfo.new("bar", "2.0"), ProjectInfo.new("bar", "2.0", refname: nil))
         assert_with_defaults(ProjectInfo.new(nil, "2.0"), ProjectInfo.new("foo", "2.0", refname: nil))

src/compiler/crystal/tools/doc/project_info.cr

@@ -6,6 +6,8 @@ module Crystal::Doc
     property refname : String? = nil
     property source_url_pattern : String? = nil
 
+    class_property git_executable = "git"
+
     def initialize(@name : String? = nil, @version : String? = nil, @refname : String? = nil, @source_url_pattern : String? = nil)
     end
 
@@ -54,7 +56,8 @@ module Crystal::Doc
     end
 
     def self.git_dir?
-      Process.run("git", ["rev-parse", "--is-inside-work-tree"]).success?
+      git_command(["rev-parse", "--is-inside-work-tree"]) { return false }
+      true
     end
 
     VERSION_TAG = /^v(\d+[-.][-.a-zA-Z\d]+)$/
@@ -112,16 +115,28 @@ module Crystal::Doc
       end
     end
 
-    def self.git_remote
-      # check whether inside git work-tree
-      status = Process.run("git", ["rev-parse", "--is-inside-work-tree"])
-      return unless status.success?
+    # Tries to run git command with args.
+    # Yields block if exec fails or process status is not success.
+    def self.git_command(args, output : Process::Stdio = Process::Redirect::Close)
+      status = Process.run(git_executable, args, output: output)
+      yield unless status.success?
+      status
+    rescue IO::Error
+      yield
+    end
 
+    def self.git_capture(args)
       io = IO::Memory.new
-      status = Process.run("git", ["remote", "-v"], output: io)
-      return unless status.success?
+      git_command(args, output: io) { yield }
+      io.to_s
+    end
 
-      remotes = io.to_s.lines.select(&.ends_with?(" (fetch)"))
+    def self.git_remote
+      # check whether inside git work-tree
+      git_command(["rev-parse", "--is-inside-work-tree"]) { return }
+
+      capture = git_capture(["remote", "-v"]) { return }
+      remotes = capture.lines.select(&.ends_with?(" (fetch)"))
 
       git_remote = remotes.find(&.starts_with?("origin\t")) || remotes.first? || return
 
@@ -133,44 +148,35 @@ module Crystal::Doc
 
     def self.git_clean?
       # Use git to determine if index and working directory are clean
-      io = IO::Memory.new
-      status = Process.run("git", ["status", "--porcelain"], output: io)
+      capture = git_capture(["status", "--porcelain"]) { return }
+
       # If clean, output of `git status --porcelain` is empty. Still need to check
       # the status code, to make sure empty doesn't mean error.
-      return unless status.success?
-      io.rewind
-      io.bytesize == 0
+      capture.bytesize == 0
     end
 
     def self.git_ref(*, branch)
-      io = IO::Memory.new
       # Check if current HEAD is tagged
-      status = Process.run("git", ["tag", "--points-at", "HEAD"], output: io)
-      return unless status.success?
-      io.rewind
-      tags = io.to_s.lines
+      capture = git_capture(["tag", "--points-at", "HEAD"]) { return }
+      tags = capture.lines
       # Return tag if commit is tagged, select first one if multiple
       if tag = tags.first?
         return tag
       end
-      io.clear
 
       if branch
         # Read current branch name
-        status = Process.run("git", ["rev-parse", "--abbrev-ref", "HEAD"], output: io)
-        return unless status.success?
+        capture = git_capture(["rev-parse", "--abbrev-ref", "HEAD"]) { return }
 
-        if branch_name = io.to_s.strip.presence
+        if branch_name = capture.strip.presence
           return branch_name
         end
-        io.clear
       end
 
       # Otherwise, return current commit sha
-      status = Process.run("git", ["rev-parse", "HEAD"], output: io)
-      return unless status.success?
+      capture = git_capture(["rev-parse", "HEAD"]) { return }
 
-      if sha = io.to_s.strip.presence
+      if sha = capture.strip.presence
         return sha
       end
     end