difftool: add various git-difftool tests

t7800-difftool.sh tests the various command-line flags,
git-config variables, and environment settings supported by
git-difftool.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7800-difftool.sh

@@ -0,0 +1,147 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 David Aguilar
+#
+
+test_description='git-difftool
+
+Testing basic diff tool invocation
+'
+
+. ./test-lib.sh
+
+remove_config_vars()
+{
+	# Unset all config variables used by git-difftool
+	git config --unset diff.tool
+	git config --unset difftool.test-tool.cmd
+	git config --unset merge.tool
+	git config --unset mergetool.test-tool.cmd
+	return 0
+}
+
+restore_test_defaults()
+{
+	# Restores the test defaults used by several tests
+	remove_config_vars
+	unset GIT_DIFF_TOOL
+	unset GIT_MERGE_TOOL
+	unset GIT_DIFFTOOL_NO_PROMPT
+	git config diff.tool test-tool &&
+	git config difftool.test-tool.cmd 'cat $LOCAL'
+}
+
+# Create a file on master and change it on branch
+test_expect_success 'setup' '
+	echo master >file &&
+	git add file &&
+	git commit -m "added file" &&
+
+	git checkout -b branch master &&
+	echo branch >file &&
+	git commit -a -m "branch changed file" &&
+	git checkout master
+'
+
+# Configure a custom difftool.<tool>.cmd and use it
+test_expect_success 'custom commands' '
+	restore_test_defaults &&
+	git config difftool.test-tool.cmd "cat \$REMOTE" &&
+
+	diff=$(git difftool --no-prompt branch) &&
+	test "$diff" = "master" &&
+
+	restore_test_defaults &&
+	diff=$(git difftool --no-prompt branch) &&
+	test "$diff" = "branch"
+'
+
+# Ensures that git-difftool ignores bogus --tool values
+test_expect_success 'difftool ignores bad --tool values' '
+	diff=$(git difftool --no-prompt --tool=bogus-tool branch)
+	test "$?" = 1 &&
+	test "$diff" = ""
+'
+
+# Specify the diff tool using $GIT_DIFF_TOOL
+test_expect_success 'GIT_DIFF_TOOL variable' '
+	git config --unset diff.tool
+	GIT_DIFF_TOOL=test-tool &&
+	export GIT_DIFF_TOOL &&
+
+	diff=$(git difftool --no-prompt branch) &&
+	test "$diff" = "branch" &&
+
+	restore_test_defaults
+'
+
+# Test the $GIT_*_TOOL variables and ensure
+# that $GIT_DIFF_TOOL always wins unless --tool is specified
+test_expect_success 'GIT_DIFF_TOOL overrides' '
+	git config diff.tool bogus-tool &&
+	git config merge.tool bogus-tool &&
+
+	GIT_MERGE_TOOL=test-tool &&
+	export GIT_MERGE_TOOL &&
+	diff=$(git difftool --no-prompt branch) &&
+	test "$diff" = "branch" &&
+	unset GIT_MERGE_TOOL &&
+
+	GIT_MERGE_TOOL=bogus-tool &&
+	GIT_DIFF_TOOL=test-tool &&
+	export GIT_MERGE_TOOL &&
+	export GIT_DIFF_TOOL &&
+
+	diff=$(git difftool --no-prompt branch) &&
+	test "$diff" = "branch" &&
+
+	GIT_DIFF_TOOL=bogus-tool &&
+	export GIT_DIFF_TOOL &&
+
+	diff=$(git difftool --no-prompt --tool=test-tool branch) &&
+	test "$diff" = "branch" &&
+
+	restore_test_defaults
+'
+
+# Test that we don't have to pass --no-prompt to difftool
+# when $GIT_DIFFTOOL_NO_PROMPT is true
+test_expect_success 'GIT_DIFFTOOL_NO_PROMPT variable' '
+	GIT_DIFFTOOL_NO_PROMPT=true &&
+	export GIT_DIFFTOOL_NO_PROMPT &&
+
+	diff=$(git difftool branch) &&
+	test "$diff" = "branch" &&
+
+	restore_test_defaults
+'
+
+# git-difftool falls back to git-mergetool config variables
+# so test that behavior here
+test_expect_success 'difftool + mergetool config variables' '
+	remove_config_vars
+	git config merge.tool test-tool &&
+	git config mergetool.test-tool.cmd "cat \$LOCAL" &&
+
+	diff=$(git difftool --no-prompt branch) &&
+	test "$diff" = "branch" &&
+
+	# set merge.tool to something bogus, diff.tool to test-tool
+	git config merge.tool bogus-tool &&
+	git config diff.tool test-tool &&
+
+	diff=$(git difftool --no-prompt branch) &&
+	test "$diff" = "branch" &&
+
+	restore_test_defaults
+'
+
+test_expect_success 'difftool.<tool>.path' '
+	git config difftool.tkdiff.path echo &&
+	diff=$(git difftool --tool=tkdiff --no-prompt branch) &&
+	git config --unset difftool.tkdiff.path &&
+	lines=$(echo "$diff" | grep file | wc -l) &&
+	test "$lines" -eq 1
+'
+
+test_done