[PATCH v2 05/15] diff tests: don't ignore "git diff" exit code in "read" loop

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Fix a test pattern that originated in f1af60bdba4 (Support 'diff=pgm'
attribute, 2007-04-22) so that we'll stop using "git diff" on the
left-hand-side of a pipe, and thus ignoring its exit code.

Rather than use intermediate files let's rewrite these tests to a much
simpler but more exhaustive "test_tmp" where we'll ignore certain
fields in the output.

Note that this is not a faithful conversion of the previous
"read/test" in some cases, as we were ignoring more fields there than
we strictly needed to. Now we'll "test_cmp" everything we can, and
only ignore the likes of paths to $TEMPDIR etc.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/t4020-diff-external.sh | 104 ++++++++++++++++++++-------------------
 1 file changed, 53 insertions(+), 51 deletions(-)

diff --git a/t/t4020-diff-external.sh b/t/t4020-diff-external.sh
index 879ee04d291..1219f8bd4c0 100755
--- a/t/t4020-diff-external.sh
+++ b/t/t4020-diff-external.sh
@@ -24,16 +24,12 @@ test_expect_success setup '
 '
 
 test_expect_success 'GIT_EXTERNAL_DIFF environment' '
-
-	GIT_EXTERNAL_DIFF=echo git diff | {
-		read path oldfile oldhex oldmode newfile newhex newmode &&
-		test "z$path" = zfile &&
-		test "z$oldmode" = z100644 &&
-		test "z$newhex" = "z$ZERO_OID" &&
-		test "z$newmode" = z100644 &&
-		oh=$(git rev-parse --verify HEAD:file) &&
-		test "z$oh" = "z$oldhex"
-	}
+	cat >expect <<-EOF &&
+	file $(git rev-parse --verify HEAD:file) 100644 file $(test_oid zero) 100644
+	EOF
+	GIT_EXTERNAL_DIFF=echo git diff >out &&
+	cut -d" " -f1,3- <out >actual &&
+	test_cmp expect actual
 
 '
 
@@ -52,15 +48,14 @@ test_expect_success 'GIT_EXTERNAL_DIFF environment and --no-ext-diff' '
 test_expect_success SYMLINKS 'typechange diff' '
 	rm -f file &&
 	ln -s elif file &&
-	GIT_EXTERNAL_DIFF=echo git diff  | {
-		read path oldfile oldhex oldmode newfile newhex newmode &&
-		test "z$path" = zfile &&
-		test "z$oldmode" = z100644 &&
-		test "z$newhex" = "z$ZERO_OID" &&
-		test "z$newmode" = z120000 &&
-		oh=$(git rev-parse --verify HEAD:file) &&
-		test "z$oh" = "z$oldhex"
-	} &&
+
+	cat >expect <<-EOF &&
+	file $(git rev-parse --verify HEAD:file) 100644 $(test_oid zero) 120000
+	EOF
+	GIT_EXTERNAL_DIFF=echo git diff >out &&
+	cut -d" " -f1,3-4,6- <out >actual &&
+	test_cmp expect actual &&
+
 	GIT_EXTERNAL_DIFF=echo git diff --no-ext-diff >actual &&
 	git diff >expect &&
 	test_cmp expect actual
@@ -70,15 +65,13 @@ test_expect_success 'diff.external' '
 	git reset --hard &&
 	echo third >file &&
 	test_config diff.external echo &&
-	git diff | {
-		read path oldfile oldhex oldmode newfile newhex newmode &&
-		test "z$path" = zfile &&
-		test "z$oldmode" = z100644 &&
-		test "z$newhex" = "z$ZERO_OID" &&
-		test "z$newmode" = z100644 &&
-		oh=$(git rev-parse --verify HEAD:file) &&
-		test "z$oh" = "z$oldhex"
-	}
+
+	cat >expect <<-EOF &&
+	file $(git rev-parse --verify HEAD:file) 100644 $(test_oid zero) 100644
+	EOF
+	git diff >out &&
+	cut -d" " -f1,3-4,6- <out >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success !SANITIZE_LEAK 'diff.external should apply only to diff' '
@@ -101,16 +94,12 @@ test_expect_success 'diff attribute' '
 
 	echo >.gitattributes "file diff=parrot" &&
 
-	git diff | {
-		read path oldfile oldhex oldmode newfile newhex newmode &&
-		test "z$path" = zfile &&
-		test "z$oldmode" = z100644 &&
-		test "z$newhex" = "z$ZERO_OID" &&
-		test "z$newmode" = z100644 &&
-		oh=$(git rev-parse --verify HEAD:file) &&
-		test "z$oh" = "z$oldhex"
-	}
-
+	cat >expect <<-EOF &&
+	file $(git rev-parse --verify HEAD:file) 100644 $(test_oid zero) 100644
+	EOF
+	git diff >out &&
+	cut -d" " -f1,3-4,6- <out >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success !SANITIZE_LEAK 'diff attribute should apply only to diff' '
@@ -132,16 +121,12 @@ test_expect_success 'diff attribute' '
 
 	echo >.gitattributes "file diff=color" &&
 
-	git diff | {
-		read path oldfile oldhex oldmode newfile newhex newmode &&
-		test "z$path" = zfile &&
-		test "z$oldmode" = z100644 &&
-		test "z$newhex" = "z$ZERO_OID" &&
-		test "z$newmode" = z100644 &&
-		oh=$(git rev-parse --verify HEAD:file) &&
-		test "z$oh" = "z$oldhex"
-	}
-
+	cat >expect <<-EOF &&
+	file $(git rev-parse --verify HEAD:file) 100644 $(test_oid zero) 100644
+	EOF
+	git diff >out &&
+	cut -d" " -f1,3-4,6- <out >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success !SANITIZE_LEAK 'diff attribute should apply only to diff' '
@@ -159,14 +144,26 @@ test_expect_success 'diff attribute and --no-ext-diff' '
 test_expect_success 'GIT_EXTERNAL_DIFF trumps diff.external' '
 	>.gitattributes &&
 	test_config diff.external "echo ext-global" &&
-	GIT_EXTERNAL_DIFF="echo ext-env" git diff | grep ext-env
+
+	cat >expect <<-EOF &&
+	ext-env file $(git rev-parse --verify HEAD:file) 100644 file $(test_oid zero) 100644
+	EOF
+	GIT_EXTERNAL_DIFF="echo ext-env" git diff >out &&
+	cut -d" " -f1-2,4- <out >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success 'attributes trump GIT_EXTERNAL_DIFF and diff.external' '
 	test_config diff.foo.command "echo ext-attribute" &&
 	test_config diff.external "echo ext-global" &&
 	echo "file diff=foo" >.gitattributes &&
-	GIT_EXTERNAL_DIFF="echo ext-env" git diff | grep ext-attribute
+
+	cat >expect <<-EOF &&
+	ext-attribute file $(git rev-parse --verify HEAD:file) 100644 file $(test_oid zero) 100644
+	EOF
+	GIT_EXTERNAL_DIFF="echo ext-env" git diff >out &&
+	cut -d" " -f1-2,4- <out >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success 'no diff with -diff' '
@@ -212,7 +209,12 @@ test_expect_success 'GIT_EXTERNAL_DIFF generates pretty paths' '
 	touch file.ext &&
 	git add file.ext &&
 	echo with extension > file.ext &&
-	GIT_EXTERNAL_DIFF=echo git diff file.ext | grep ......_file\.ext &&
+
+	cat >expect <<-EOF &&
+	file.ext file $(git rev-parse --verify HEAD:file) 100644 file.ext $(test_oid zero) 100644
+	EOF
+	GIT_EXTERNAL_DIFF=echo git diff file.ext >out &&
+	cut -d" " -f1,3- <out >actual &&
 	git update-index --force-remove file.ext &&
 	rm file.ext
 '
-- 
2.35.1.1242.gfeba0eae32b