[PATCH v2 1/2] t4211: fix broken test when one -L range is subset of another

[Eric Sunshine <sunshine@sunshineco.com>]

t4211 attempts to test multiple git-log -L ranges where one range is a
superset of the other, and falsely succeeds because its "expected"
output is incorrect.

Overlapping -L ranges handed to git-log are coalesced by
line-log.c:sort_and_merge_range_set() into a set of non-overlapping,
disjoint ranges. When one range is a subset of another,
sort_and_merge_range_set() should coalesce both ranges to the superset
range, but instead the coalesced range often is incorrectly truncated to
the end of the subset range. For example, ranges 2-8 and 3-4 are
coalesced incorrectly to 2-4.

One can observe this incorrect behavior with git-log -L using the test
repository created by t4211. The superset/subset ranges t4211 employs
are 4-$ and 8-12 (where $ represents end-of-file). The coalesced range
should be 4-$. Manually invoking git-log with the same ranges the test
employs, we see:

  % git log -L 4:a.c simple |
    awk '/^commit [0-9a-f]{40}/ { print substr($2,1,7) }'
  4659538
  100b61a
  39b6eb2
  a6eb826
  f04fb20
  de4c48a

  % git log -L 8,12:a.c simple | awk ...
  f04fb20
  de4c48a

  % git log -L 4:a.c -L 8,12:a.c simple | awk ...
  a6eb826
  f04fb20
  de4c48a

This last output is incorrect. 8-12 is a subset of 4-$, hence the output
of the coalesced range should be the same as the 4-$ output shown first.
In fact, the above incorrect output is the truncated bogus range 4-12:

  % git log -L 4,12:a.c simple | awk ...
  a6eb826
  f04fb20
  de4c48a

Fix the test to correctly fail in the presence of the
sort_and_merge_range_set() coalescing bug. Do so by changing the
"expected" output to the commits mentioned in the 4-$ output above.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
---
 t/t4211-line-log.sh              |   4 +-
 t/t4211/expect.multiple-superset | 134 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 133 insertions(+), 5 deletions(-)

diff --git a/t/t4211-line-log.sh b/t/t4211-line-log.sh
index 7776f93..549df9e 100755
--- a/t/t4211-line-log.sh
+++ b/t/t4211-line-log.sh
@@ -50,8 +50,8 @@ canned_test "-M -L ':f:b.c' parallel-change" parallel-change-f-to-main
 canned_test "-L 4,12:a.c -L :main:a.c simple" multiple
 canned_test "-L 4,18:a.c -L :main:a.c simple" multiple-overlapping
 canned_test "-L :main:a.c -L 4,18:a.c simple" multiple-overlapping
-canned_test "-L 4:a.c -L 8,12:a.c simple" multiple-superset
-canned_test "-L 8,12:a.c -L 4:a.c simple" multiple-superset
+canned_test_failure "-L 4:a.c -L 8,12:a.c simple" multiple-superset
+canned_test_failure "-L 8,12:a.c -L 4:a.c simple" multiple-superset
 
 test_bad_opts "-L" "switch.*requires a value"
 test_bad_opts "-L b.c" "argument.*not of the form"
diff --git a/t/t4211/expect.multiple-superset b/t/t4211/expect.multiple-superset
index a1f5bc4..d930b6e 100644
--- a/t/t4211/expect.multiple-superset
+++ b/t/t4211/expect.multiple-superset
@@ -1,3 +1,100 @@
+commit 4659538844daa2849b1a9e7d6fadb96fcd26fc83
+Author: Thomas Rast <trast@student.ethz.ch>
+Date:   Thu Feb 28 10:48:43 2013 +0100
+
+    change back to complete line
+
+diff --git a/a.c b/a.c
+--- a/a.c
++++ b/a.c
+@@ -4,19 +4,21 @@
+ long f(long x)
+ {
+ 	int s = 0;
+ 	while (x) {
+ 		x >>= 1;
+ 		s++;
+ 	}
+ 	return s;
+ }
+ 
+ /*
+  * This is only an example!
+  */
+ 
+ int main ()
+ {
+ 	printf("%ld\n", f(15));
+ 	return 0;
+-}
+\ No newline at end of file
++}
++
++/* incomplete lines are bad! */
+
+commit 100b61a6f2f720f812620a9d10afb3a960ccb73c
+Author: Thomas Rast <trast@student.ethz.ch>
+Date:   Thu Feb 28 10:48:10 2013 +0100
+
+    change to an incomplete line at end
+
+diff --git a/a.c b/a.c
+--- a/a.c
++++ b/a.c
+@@ -4,19 +4,19 @@
+ long f(long x)
+ {
+ 	int s = 0;
+ 	while (x) {
+ 		x >>= 1;
+ 		s++;
+ 	}
+ 	return s;
+ }
+ 
+ /*
+  * This is only an example!
+  */
+ 
+ int main ()
+ {
+ 	printf("%ld\n", f(15));
+ 	return 0;
+-}
++}
+\ No newline at end of file
+
+commit 39b6eb2d5b706d3322184a169f666f25ed3fbd00
+Author: Thomas Rast <trast@student.ethz.ch>
+Date:   Thu Feb 28 10:45:41 2013 +0100
+
+    touch comment
+
+diff --git a/a.c b/a.c
+--- a/a.c
++++ b/a.c
+@@ -3,19 +3,19 @@
+ long f(long x)
+ {
+ 	int s = 0;
+ 	while (x) {
+ 		x >>= 1;
+ 		s++;
+ 	}
+ 	return s;
+ }
+ 
+ /*
+- * A comment.
++ * This is only an example!
+  */
+ 
+ int main ()
+ {
+ 	printf("%ld\n", f(15));
+ 	return 0;
+ }
+
 commit a6eb82647d5d67f893da442f8f9375fd89a3b1e2
 Author: Thomas Rast <trast@student.ethz.ch>
 Date:   Thu Feb 28 10:45:16 2013 +0100
@@ -7,7 +104,7 @@ Date:   Thu Feb 28 10:45:16 2013 +0100
 diff --git a/a.c b/a.c
 --- a/a.c
 +++ b/a.c
-@@ -3,9 +3,9 @@
+@@ -3,19 +3,19 @@
 -int f(int x)
 +long f(long x)
  {
@@ -18,6 +115,17 @@ diff --git a/a.c b/a.c
  	}
  	return s;
  }
+ 
+ /*
+  * A comment.
+  */
+ 
+ int main ()
+ {
+-	printf("%d\n", f(15));
++	printf("%ld\n", f(15));
+ 	return 0;
+ }
 
 commit f04fb20f2c77850996cba739709acc6faecc58f7
 Author: Thomas Rast <trast@student.ethz.ch>
@@ -28,7 +136,7 @@ Date:   Thu Feb 28 10:44:55 2013 +0100
 diff --git a/a.c b/a.c
 --- a/a.c
 +++ b/a.c
-@@ -3,8 +3,9 @@
+@@ -3,18 +3,19 @@
  int f(int x)
  {
  	int s = 0;
@@ -38,6 +146,16 @@ diff --git a/a.c b/a.c
  	}
 +	return s;
  }
+ 
+ /*
+  * A comment.
+  */
+ 
+ int main ()
+ {
+ 	printf("%d\n", f(15));
+ 	return 0;
+ }
 
 commit de4c48ae814792c02a49c4c3c0c757ae69c55f6a
 Author: Thomas Rast <trast@student.ethz.ch>
@@ -48,7 +166,7 @@ Date:   Thu Feb 28 10:44:48 2013 +0100
 diff --git a/a.c b/a.c
 --- /dev/null
 +++ b/a.c
-@@ -0,0 +3,8 @@
+@@ -0,0 +3,18 @@
 +int f(int x)
 +{
 +	int s = 0;
@@ -57,3 +175,13 @@ diff --git a/a.c b/a.c
 +		s++;
 +	}
 +}
++
++/*
++ * A comment.
++ */
++
++int main ()
++{
++	printf("%d\n", f(15));
++	return 0;
++}
-- 
1.8.3.2