[PATCH v3 8/9] test-lib: test_region looks for trace2 regions

From: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date: Jan 23, 2021, 19:58 UTC
Message-ID: <b37181bdec43cfc798740f2bdd19f6d2482beb26.1611431900.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.839.v3.git.1611431899.gitgitgadget@gmail.com>

From: Derrick Stolee <dstolee@microsoft.com>

Most test cases can verify Git's behavior using input/output expectations or changes to the .git directory. However, sometimes we want to check that Git did or did not run a certain section of code. This is particularly important for performance-only features that we want to ensure have been enabled in certain cases.

Add a new 'test_region' function that checks if a trace2 region was entered and left in a given trace2 event log.

There is one existing test (t0500-progress-display.sh) that performs this check already, so use the helper function instead. Note that this changes the expectations slightly. The old test (incorrectly) used two patterns for the 'grep' invocation, but this performs an OR of the patterns, not an AND. This means that as long as one region_enter event was logged, the test would succeed, even if it was not due to the progress category.

More uses will be added in a later change.

t6423-merge-rename-directories.sh also greps for region_enter lines, but it verifies the number of such lines, which is not the same as an existence check.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 t/t0500-progress-display.sh |  3 +--
 t/test-lib-functions.sh     | 42 +++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/t/t0500-progress-display.sh b/t/t0500-progress-display.sh
index 1ed1df351cb..84cce345e7d 100755
--- a/t/t0500-progress-display.sh
+++ b/t/t0500-progress-display.sh
@@ -303,8 +303,7 @@ test_expect_success 'progress generates traces' '
 		"Working hard" <in 2>stderr &&
 
 	# t0212/parse_events.perl intentionally omits regions and data.
-	grep -e "region_enter" -e "\"category\":\"progress\"" trace.event &&
-	grep -e "region_leave" -e "\"category\":\"progress\"" trace.event &&
+	test_region progress "Working hard" trace.event &&
 	grep "\"key\":\"total_objects\",\"value\":\"40\"" trace.event &&
 	grep "\"key\":\"total_bytes\",\"value\":\"409600\"" trace.event
 '
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 999982fe4a9..3f425deba18 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -1655,3 +1655,45 @@ test_subcommand () {
 		grep "\[$expr\]"
 	fi
 }
+
+# Check that the given command was invoked as part of the
+# trace2-format trace on stdin.
+#
+#	test_region [!] <category> <label> git <command> <args>...
+#
+# For example, to look for trace2_region_enter("index", "do_read_index", repo)
+# in an invocation of "git checkout HEAD~1", run
+#
+#	GIT_TRACE2_EVENT="$(pwd)/trace.txt" GIT_TRACE2_EVENT_NESTING=10 \
+#		git checkout HEAD~1 &&
+#	test_region index do_read_index <trace.txt
+#
+# If the first parameter passed is !, this instead checks that
+# the given region was not entered.
+#
+test_region () {
+	local expect_exit=0
+	if test "$1" = "!"
+	then
+		expect_exit=1
+		shift
+	fi
+
+	grep -e	'"region_enter".*"category":"'"$1"'","label":"'"$2"\" "$3"
+	exitcode=$?
+
+	if test $exitcode != $expect_exit = 1]
+	then
+		return 1
+	fi
+
+	grep -e	'"region_leave".*"category":"'"$1"'","label":"'"$2"\" "$3"
+	exitcode=$?
+
+	if test $exitcode != $expect_exit = 1]
+	then
+		return 1
+	fi
+
+	return 0
+}

-- 
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