fast-import: add input format tests

Documentation/git-fast-import.txt says that git-fast-import is strict
about it's input format. But committer/author field parsing is a bit
loose. Invalid values can be unnoticed and written out to the commit,
either with format-conforming input or with non-format-conforming one.

Add one passing and one failing test for empty/absent committer name
with well-formed input. And a failed test with unnoticed ill-formed
input.

Reported-by: SASAKI Suguru <sss.sonik@gmail.com>
Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9300-fast-import.sh

@@ -324,6 +324,105 @@ test_expect_success \
 	 test `git rev-parse master` = `git rev-parse TEMP_TAG^`'
 rm -f .git/TEMP_TAG
 
+git gc 2>/dev/null >/dev/null
+git prune 2>/dev/null >/dev/null
+
+cat >input <<INPUT_END
+commit refs/heads/empty-committer-1
+committer  <> $GIT_COMMITTER_DATE
+data <<COMMIT
+empty commit
+COMMIT
+INPUT_END
+test_expect_success 'B: accept empty committer' '
+	git fast-import <input &&
+	out=$(git fsck) &&
+	echo "$out" &&
+	test -z "$out"
+'
+git update-ref -d refs/heads/empty-committer-1 || true
+
+git gc 2>/dev/null >/dev/null
+git prune 2>/dev/null >/dev/null
+
+cat >input <<INPUT_END
+commit refs/heads/empty-committer-2
+committer <a@b.com> $GIT_COMMITTER_DATE
+data <<COMMIT
+empty commit
+COMMIT
+INPUT_END
+test_expect_failure 'B: accept and fixup committer with no name' '
+	git fast-import <input &&
+	out=$(git fsck) &&
+	echo "$out" &&
+	test -z "$out"
+'
+git update-ref -d refs/heads/empty-committer-2 || true
+
+git gc 2>/dev/null >/dev/null
+git prune 2>/dev/null >/dev/null
+
+cat >input <<INPUT_END
+commit refs/heads/invalid-committer
+committer Name email> $GIT_COMMITTER_DATE
+data <<COMMIT
+empty commit
+COMMIT
+INPUT_END
+test_expect_failure 'B: fail on invalid committer (1)' '
+	test_must_fail git fast-import <input
+'
+git update-ref -d refs/heads/invalid-committer || true
+
+cat >input <<INPUT_END
+commit refs/heads/invalid-committer
+committer Name <e<mail> $GIT_COMMITTER_DATE
+data <<COMMIT
+empty commit
+COMMIT
+INPUT_END
+test_expect_failure 'B: fail on invalid committer (2)' '
+	test_must_fail git fast-import <input
+'
+git update-ref -d refs/heads/invalid-committer || true
+
+cat >input <<INPUT_END
+commit refs/heads/invalid-committer
+committer Name <email>> $GIT_COMMITTER_DATE
+data <<COMMIT
+empty commit
+COMMIT
+INPUT_END
+test_expect_failure 'B: fail on invalid committer (3)' '
+	test_must_fail git fast-import <input
+'
+git update-ref -d refs/heads/invalid-committer || true
+
+cat >input <<INPUT_END
+commit refs/heads/invalid-committer
+committer Name <email $GIT_COMMITTER_DATE
+data <<COMMIT
+empty commit
+COMMIT
+INPUT_END
+test_expect_failure 'B: fail on invalid committer (4)' '
+	test_must_fail git fast-import <input
+'
+git update-ref -d refs/heads/invalid-committer || true
+
+cat >input <<INPUT_END
+commit refs/heads/invalid-committer
+committer Name<email> $GIT_COMMITTER_DATE
+data <<COMMIT
+empty commit
+COMMIT
+INPUT_END
+test_expect_failure 'B: fail on invalid committer (5)' '
+	test_must_fail git fast-import <input
+'
+git update-ref -d refs/heads/invalid-committer || true
+
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