Fix: don't crash when git binary is missing

CHANGELOG.md

@@ -1,5 +1,10 @@
 # CHANGELOG
 
+## Unreleased
+
+Fixes:
+- Don't crash when git binary is missing.
+
 ## v0.6.1
 
 Fixes:

src/resolvers/git.cr

@@ -6,13 +6,14 @@ module Shards
 
  class GitResolver < Resolver
  # :nodoc:
- GIT_SHA1 = /\A[0-9a-f]{40}\Z/
-
- # :nodoc:
- GIT_VERSION = `git --version`.strip[12 .. -1]
+ def self.git_version
+ @@git_version ||= `git --version`.strip[12 .. -1]
+ end
 
  # :nodoc:
- GIT_COLUMN_NEVER = Helpers::NaturalSort.sort(GIT_VERSION, "1.7.11") < 0 ? "--column=never" : ""
+ def self.git_column_never
+ @@git_column_never ||= Helpers::NaturalSort.sort(git_version, "1.7.11") < 0 ? "--column=never" : ""
+ end
 
  def self.key
  "git"
@@ -41,7 +42,7 @@ module Shards
  versions = if refs = dependency.refs
  [version_at(refs), refs]
  else
- capture("git tag --list #{ GIT_COLUMN_NEVER }")
+ capture("git tag --list #{ GitResolver.git_column_never }")
  .split("\n")
  .map { |version| $1 if version.strip =~ RELEASE_VERSION }
  end.compact
@@ -56,12 +57,12 @@ module Shards
 
  def matches?(commit)
  if branch = dependency["branch"]?
- capture("git branch --list #{ GIT_COLUMN_NEVER } --contains #{ commit }")
+ capture("git branch --list #{ GitResolver.git_column_never } --contains #{ commit }")
  .split("\n")
  .compact_map { |line| $1? if line =~ /^[* ] (.+)$/ }
  .includes?(branch)
  elsif tag = dependency["tag"]?
- capture("git tag --list #{ GIT_COLUMN_NEVER } --contains #{ commit }")
+ capture("git tag --list #{ GitResolver.git_column_never } --contains #{ commit }")
  .split("\n")
  .includes?(tag)
  else
@@ -136,7 +137,7 @@ module Shards
  private def version_at(refs)
  update_local_cache
 
- tags = capture("git tag --list --contains #{refs} #{ GIT_COLUMN_NEVER }")
+ tags = capture("git tag --list --contains #{refs} #{ GitResolver.git_column_never }")
  .split("\n")
  .map { |tag| $1 if tag =~ RELEASE_VERSION }
  .compact
@@ -148,8 +149,8 @@ module Shards
 
  refs = [] of String?
  refs << commit
- refs += capture("git tag --list --contains #{commit} #{ GIT_COLUMN_NEVER }").split("\n")
- refs += capture("git branch --list --contains #{commit} #{ GIT_COLUMN_NEVER }").split(" ")
+ refs += capture("git tag --list --contains #{commit} #{ GitResolver.git_column_never }").split("\n")
+ refs += capture("git branch --list --contains #{commit} #{ GitResolver.git_column_never }").split(" ")
  refs.compact.uniq
  end
 
@@ -224,7 +225,7 @@ module Shards
  if str.starts_with?("error: ") && (idx = str.index('\n'))
  message = str[7 ... idx]
  end
- raise Error.new("git command failed: #{ command } (#{ message })")
+ raise Error.new("git command failed: #{ command } (#{ message }). Maybe you didn't install git?")
  end
  end
  end