[RFC PATCH 3/3] diff: check MIN_BLOCK_LENGTH at start of new block

[Jonathan Tan]

When noticing that the current line is not the continuation of the
current block, but the start of a new one, mark_color_as_moved() does
not check the length of the current block. Perform that check.

Signed-off-by: Jonathan Tan <jonathanta...@google.com>
---
 diff.c                     |  6 +++++-
 t/t4015-diff-whitespace.sh | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/diff.c b/diff.c
index 95620b130..04fc0d65d 100644
--- a/diff.c
+++ b/diff.c
@@ -920,7 +920,6 @@ static void mark_color_as_moved(struct diff_options *o,
                }
 
                l->flags |= DIFF_SYMBOL_MOVED_LINE;
-               block_length++;
 
                if (o->color_moved == COLOR_MOVED_PLAIN)
                        continue;
@@ -950,8 +949,13 @@ static void mark_color_as_moved(struct diff_options *o,
                        }
 
                        flipped_block = (flipped_block + 1) % 2;
+
+                       adjust_last_block(o, n, block_length);
+                       block_length = 0;
                }
 
+               block_length++;
+
                if (flipped_block)
                        l->flags |= DIFF_SYMBOL_MOVED_LINE_ALT;
        }
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 6f7758e5c..401dc8f08 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1015,7 +1015,7 @@ test_expect_success 'detect moved code, complete file' '
        test_cmp expected actual
 '
 
-test_expect_success 'detect malicious moved code, inside file' '
+test_expect_failure 'detect malicious moved code, inside file' '
        test_config color.diff.oldMoved "normal red" &&
        test_config color.diff.newMoved "normal green" &&
        test_config color.diff.oldMovedAlternative "blue" &&
@@ -1417,6 +1417,49 @@ test_expect_success '--color-moved block at end of diff 
output respects MIN_BLOC
        test_cmp expected actual
 '
 
+test_expect_success '--color-moved treats adjacent blocks as separate for 
MIN_BLOCK_LENGTH' '
+       git reset --hard &&
+       cat <<-\EOF >foo &&
+       line1
+       irrelevant_line
+       line2
+       line3
+       EOF
+       >bar &&
+       git add foo bar &&
+       git commit -m x &&
+
+       cat <<-\EOF >foo &&
+       irrelevant_line
+       EOF
+       cat <<-\EOF >bar &&
+       line2
+       line3
+       line1
+       EOF
+
+       git diff HEAD --color-moved=zebra --no-renames | grep -v "index" | 
test_decode_color >actual &&
+       cat >expected <<-\EOF &&
+       <BOLD>diff --git a/bar b/bar<RESET>
+       <BOLD>--- a/bar<RESET>
+       <BOLD>+++ b/bar<RESET>
+       <CYAN>@@ -0,0 +1,3 @@<RESET>
+       <GREEN>+<RESET><GREEN>line2<RESET>
+       <GREEN>+<RESET><GREEN>line3<RESET>
+       <GREEN>+<RESET><GREEN>line1<RESET>
+       <BOLD>diff --git a/foo b/foo<RESET>
+       <BOLD>--- a/foo<RESET>
+       <BOLD>+++ b/foo<RESET>
+       <CYAN>@@ -1,4 +1 @@<RESET>
+       <RED>-line1<RESET>
+        irrelevant_line<RESET>
+       <RED>-line2<RESET>
+       <RED>-line3<RESET>
+       EOF
+
+       test_cmp expected actual
+'
+
 test_expect_success 'move detection with submodules' '
        test_create_repo bananas &&
        echo ripe >bananas/recipe &&
-- 
2.14.0.434.g98096fd7a8-goog