6 files changed, 314 insertions, 0 deletions
diff --git a/t/t4051-diff-function-context.sh b/t/t4051-diff-function-context.sh
new file mode 100755
index 0000000..725278a
--- /dev/null
+++ b/t/t4051-diff-function-context.sh
@@ -0,0 +1,213 @@
+#!/bin/sh
+
+test_description='diff function context'
+
+TEST_PASSES_SANITIZE_LEAK=true
+. ./test-lib.sh
+
+dir="$TEST_DIRECTORY/t4051"
+
+commit_and_tag () {
+	tag=$1 &&
+	shift &&
+	git add "$@" &&
+	test_tick &&
+	git commit -m "$tag" &&
+	git tag "$tag"
+}
+
+first_context_line () {
+	awk '
+		found {print; exit}
+		/^@@/ {found = 1}
+	'
+}
+
+last_context_line () {
+	sed -ne \$p
+}
+
+check_diff () {
+	name=$1
+	desc=$2
+	options="-W $3"
+
+	test_expect_success "$desc" '
+		git diff $options "$name^" "$name" >"$name.diff"
+	'
+
+	test_expect_success ' diff applies' '
+		test_when_finished "git reset --hard" &&
+		git checkout --detach "$name^" &&
+		git apply --index "$name.diff" &&
+		git diff --exit-code "$name"
+	'
+}
+
+test_expect_success 'setup' '
+	cat "$dir/includes.c" "$dir/dummy.c" "$dir/dummy.c" "$dir/hello.c" \
+		"$dir/dummy.c" "$dir/dummy.c" >file.c &&
+	commit_and_tag initial file.c &&
+
+	grep -v "delete me from hello" <file.c >file.c.new &&
+	mv file.c.new file.c &&
+	commit_and_tag changed_hello file.c &&
+
+	grep -v "delete me from includes" <file.c >file.c.new &&
+	mv file.c.new file.c &&
+	commit_and_tag changed_includes file.c &&
+
+	cat "$dir/appended1.c" >>file.c &&
+	commit_and_tag appended file.c &&
+
+	cat "$dir/appended2.c" >>file.c &&
+	commit_and_tag extended file.c &&
+
+	grep -v "Begin of second part" <file.c >file.c.new &&
+	mv file.c.new file.c &&
+	commit_and_tag long_common_tail file.c &&
+
+	git checkout initial &&
+	cat "$dir/hello.c" "$dir/dummy.c" >file.c &&
+	commit_and_tag hello_dummy file.c &&
+
+	# overlap function context of 1st change and -u context of 2nd change
+	grep -v "delete me from hello" <"$dir/hello.c" >file.c &&
+	sed "2a\\
+	     extra line" <"$dir/dummy.c" >>file.c &&
+	commit_and_tag changed_hello_dummy file.c &&
+
+	git checkout initial &&
+	grep -v "delete me from hello" <file.c >file.c.new &&
+	mv file.c.new file.c &&
+	cat "$dir/appended1.c" >>file.c &&
+	commit_and_tag changed_hello_appended file.c
+'
+
+check_diff changed_hello 'changed function'
+
+test_expect_success ' context includes comment' '
+	grep "^ .*Hello comment" changed_hello.diff
+'
+
+test_expect_success ' context includes begin' '
+	grep "^ .*Begin of hello" changed_hello.diff
+'
+
+test_expect_success ' context includes end' '
+	grep "^ .*End of hello" changed_hello.diff
+'
+
+test_expect_success ' context does not include other functions' '
+	test $(grep -c "^[ +-].*Begin" changed_hello.diff) -le 1
+'
+
+test_expect_success ' context does not include preceding empty lines' '
+	test "$(first_context_line <changed_hello.diff)" != " "
+'
+
+test_expect_success ' context does not include trailing empty lines' '
+	test "$(last_context_line <changed_hello.diff)" != " "
+'
+
+check_diff changed_includes 'changed includes'
+
+test_expect_success ' context includes begin' '
+	grep "^ .*Begin.h" changed_includes.diff
+'
+
+test_expect_success ' context includes end' '
+	grep "^ .*End.h" changed_includes.diff
+'
+
+test_expect_success ' context does not include other functions' '
+	test $(grep -c "^[ +-].*Begin" changed_includes.diff) -le 1
+'
+
+test_expect_success ' context does not include trailing empty lines' '
+	test "$(last_context_line <changed_includes.diff)" != " "
+'
+
+check_diff appended 'appended function'
+
+test_expect_success ' context includes begin' '
+	grep "^[+].*Begin of first part" appended.diff
+'
+
+test_expect_success ' context includes end' '
+	grep "^[+].*End of first part" appended.diff
+'
+
+test_expect_success ' context does not include other functions' '
+	test $(grep -c "^[ +-].*Begin" appended.diff) -le 1
+'
+
+check_diff extended 'appended function part'
+
+test_expect_success ' context includes begin' '
+	grep "^ .*Begin of first part" extended.diff
+'
+
+test_expect_success ' context includes end' '
+	grep "^[+].*End of second part" extended.diff
+'
+
+test_expect_success ' context does not include other functions' '
+	test $(grep -c "^[ +-].*Begin" extended.diff) -le 2
+'
+
+test_expect_success ' context does not include preceding empty lines' '
+	test "$(first_context_line <extended.diff)" != " "
+'
+
+check_diff long_common_tail 'change with long common tail and no context' -U0
+
+test_expect_success ' context includes begin' '
+	grep "^ .*Begin of first part" long_common_tail.diff
+'
+
+test_expect_success ' context includes end' '
+	grep "^ .*End of second part" long_common_tail.diff
+'
+
+test_expect_success ' context does not include other functions' '
+	test $(grep -c "^[ +-].*Begin" long_common_tail.diff) -le 2
+'
+
+test_expect_success ' context does not include preceding empty lines' '
+	test "$(first_context_line <long_common_tail.diff)" != " "
+'
+
+check_diff changed_hello_appended 'changed function plus appended function'
+
+test_expect_success ' context includes begin' '
+	grep "^ .*Begin of hello" changed_hello_appended.diff &&
+	grep "^[+].*Begin of first part" changed_hello_appended.diff
+'
+
+test_expect_success ' context includes end' '
+	grep "^ .*End of hello" changed_hello_appended.diff &&
+	grep "^[+].*End of first part" changed_hello_appended.diff
+'
+
+test_expect_success ' context does not include other functions' '
+	test $(grep -c "^[ +-].*Begin" changed_hello_appended.diff) -le 2
+'
+
+check_diff changed_hello_dummy 'changed two consecutive functions'
+
+test_expect_success ' context includes begin' '
+	grep "^ .*Begin of hello" changed_hello_dummy.diff &&
+	grep "^ .*Begin of dummy" changed_hello_dummy.diff
+'
+
+test_expect_success ' context includes end' '
+	grep "^ .*End of hello" changed_hello_dummy.diff &&
+	grep "^ .*End of dummy" changed_hello_dummy.diff
+'
+
+test_expect_success ' overlapping hunks are merged' '
+	test $(grep -c "^@@" changed_hello_dummy.diff) -eq 1
+'
+
+test_done
diff --git a/t/t4051/appended1.c b/t/t4051/appended1.c
new file mode 100644
index 0000000..a9f56f1
--- /dev/null
+++ b/t/t4051/appended1.c
@@ -0,0 +1,15 @@
+
+int appended(void) // Begin of first part
+{
+	int i;
+	char *s = "a string";
+
+	printf("%s\n", s);
+
+	for (i = 99;
+	     i >= 0;
+	     i--) {
+		printf("%d bottles of beer on the wall\n", i);
+	}
+
+	printf("End of first part\n");
diff --git a/t/t4051/appended2.c b/t/t4051/appended2.c
new file mode 100644
index 0000000..e651f71
--- /dev/null
+++ b/t/t4051/appended2.c
@@ -0,0 +1,35 @@
+	printf("Begin of second part\n");
+
+	/*
+	 * Lorem ipsum dolor sit amet, consectetuer sadipscing elitr,
+	 * sed diam nonumy eirmod tempor invidunt ut labore et dolore
+	 * magna aliquyam erat, sed diam voluptua. At vero eos et
+	 * accusam et justo duo dolores et ea rebum. Stet clita kasd
+	 * gubergren, no sea takimata sanctus est Lorem ipsum dolor
+	 * sit amet.
+	 *
+	 * Lorem ipsum dolor sit amet, consectetuer sadipscing elitr,
+	 * sed diam nonumy eirmod tempor invidunt ut labore et dolore
+	 * magna aliquyam erat, sed diam voluptua. At vero eos et
+	 * accusam et justo duo dolores et ea rebum. Stet clita kasd
+	 * gubergren, no sea takimata sanctus est Lorem ipsum dolor
+	 * sit amet.
+	 *
+	 * Lorem ipsum dolor sit amet, consectetuer sadipscing elitr,
+	 * sed diam nonumy eirmod tempor invidunt ut labore et dolore
+	 * magna aliquyam erat, sed diam voluptua. At vero eos et
+	 * accusam et justo duo dolores et ea rebum. Stet clita kasd
+	 * gubergren, no sea takimata sanctus est Lorem ipsum dolor
+	 * sit amet.
+	 *
+	 * Lorem ipsum dolor sit amet, consectetuer sadipscing elitr,
+	 * sed diam nonumy eirmod tempor invidunt ut labore et dolore
+	 * magna aliquyam erat, sed diam voluptua. At vero eos et
+	 * accusam et justo duo dolores et ea rebum. Stet clita kasd
+	 * gubergren, no sea takimata sanctus est Lorem ipsum dolor
+	 * sit amet.
+	 *
+	 */
+
+	return 0;
+}	// End of second part
diff --git a/t/t4051/dummy.c b/t/t4051/dummy.c
new file mode 100644
index 0000000..a43016e
--- /dev/null
+++ b/t/t4051/dummy.c
@@ -0,0 +1,7 @@
+
+static int dummy(void)	// Begin of dummy
+{
+	int rc = 0;
+
+	return rc;
+}	// End of dummy
diff --git a/t/t4051/hello.c b/t/t4051/hello.c
new file mode 100644
index 0000000..73e767e
--- /dev/null
+++ b/t/t4051/hello.c
@@ -0,0 +1,24 @@
+
+/*
+ * Hello comment.
+ */
+static void hello(void)	// Begin of hello
+{
+	/*
+	 * Classic.
+	 */
+	putchar('H');
+	putchar('e');
+	putchar('l');
+	putchar('l');
+	putchar('o');
+	putchar(' ');
+	/* delete me from hello */
+	putchar('w');
+	putchar('o');
+	putchar('r');
+	putchar('l');
+	putchar('d');
+	putchar('.');
+	putchar('\n');
+}	// End of hello
diff --git a/t/t4051/includes.c b/t/t4051/includes.c
new file mode 100644
index 0000000..efc68f8
--- /dev/null
+++ b/t/t4051/includes.c
@@ -0,0 +1,20 @@
+#include <Begin.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdarg.h>
+/* delete me from includes */
+#include <string.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/time.h>
+#include <time.h>
+#include <signal.h>
+#include <assert.h>
+#include <regex.h>
+#include <utime.h>
+#include <syslog.h>
+#include <End.h>