test: use completely isolated, temporary GIT_CONFIG

This writes a temp git config file during setup/teardown, and exports
GIT_CONFIG=… to that and sets GIT_CONFIG_NOSYSTEM=1. This ensures that
any git invocations _only_ use that configuration.

Note that none of the tests currently test anything other than the
default config; however, if they do, the generation of this test config
should be moved into `setup()` rather than `setup_file()` so that it can
be modified and restored between tests.

Author: rwe

diff-so-fancy

@@ -490,26 +490,12 @@ sub git_config_boolean {
 	my $search_key    = lc($_[0] || "");
 	my $default_value = lc($_[1] || 0); # Default to false
 
-	# If we're in a unit test, use the default (don't read the users config)
-	if (in_unit_test()) {
-		return boolean($default_value);
-	}
-
 	my $result = git_config($search_key,$default_value);
 	my $ret    = boolean($result);
 
 	return $ret;
 }
 
-# Check if we're inside of BATS
-sub in_unit_test {
-	if ($ENV{BATS_CWD}) {
-		return 1;
-	} else {
-		return 0;
-	}
-}
-
 sub get_less_charset {
 	my @less_char_vars = ("LESSCHARSET", "LESSCHARDEF", "LC_ALL", "LC_CTYPE", "LANG");
 	foreach my $key (@less_char_vars) {

test/bugs.bats

@@ -9,12 +9,17 @@ __load_imports__() {
 
 setup_file() {
 	__load_imports__
+	setup_default_dsf_git_config
 }
 
 setup() {
 	__load_imports__
 }
 
+teardown_file() {
+	teardown_default_dsf_git_config
+}
+
 # https://github.com/paulirish/dotfiles/commit/6743b907ff586c28cd36e08d1e1c634e2968893e#commitcomment-13459061
 @test "All removed lines are present in diff" {
   output=$( load_fixture "chromium-modaltoelement" | $diff_so_fancy )

test/diff-so-fancy.bats

@@ -10,14 +10,19 @@ __load_imports__() {
 setup_file() {
 	__load_imports__
 	set_env
+	setup_default_dsf_git_config
 	# bats fails to handle our multiline result, so we save to $output ourselves
-	__dfs_cached_output="$( load_fixture "ls-function" | $diff_so_fancy )"
-	export __dfs_cached_output
+	__dsf_cached_output="$( load_fixture "ls-function" | $diff_so_fancy )"
+	export __dsf_cached_output
 }
 
 setup() {
 	__load_imports__
-	output="${__dfs_cached_output}"
+	output="${__dsf_cached_output}"
+}
+
+teardown_file() {
+	teardown_default_dsf_git_config
 }
 
 @test "diff-so-fancy runs and exits without error" {

test/test_helper/util.bash

@@ -10,17 +10,36 @@ set_env() {
   export LC_CTYPE="en_US.UTF-8"
 }
 
+dsf_test_git_config() {
+  printf '%s/gitconfig' "${BATS_TMPDIR}"
+}
 
 # applying colors so ANSI color values will match
 # FIXME: not everyone will have these set, so we need to test for that.
-git config color.diff.meta "227"
-git config color.diff.frag "magenta bold"
-git config color.diff.commit "227 bold"
-git config color.diff.old "red bold"
-git config color.diff.new "green bold"
-git config color.diff.whitespace "red reverse"
+setup_default_dsf_git_config() {
+  GIT_CONFIG="$(dsf_test_git_config)" || return $?
+  cat > "${GIT_CONFIG}" <<EOF || return $?
+[color "diff"]
+	meta = 227
+	frag = magenta bold
+	commit = 227 bold
+	old = red bold
+	new = green bold
+	whitespace = red reverse
+
+[color "diff-highlight"]
+	oldNormal = red bold
+	oldHighlight = red bold 52
+	newNormal = green bold
+	newHighlight = green bold 22
+EOF
+  export GIT_CONFIG
+  export GIT_CONFIG_NOSYSTEM=1
+}
 
-git config color.diff-highlight.oldNormal "red bold"
-git config color.diff-highlight.oldHighlight "red bold 52"
-git config color.diff-highlight.newNormal "green bold"
-git config color.diff-highlight.newHighlight "green bold 22"
+teardown_default_dsf_git_config() {
+  local test_config
+  test_config="$(dsf_test_git_config)" || return $?
+  [ ! -f "${test_config}" ] || rm -f "${test_config}"
+  GIT_CONFIG=/dev/null
+}