wal_utils: Improve regression tests

Instead of some weird COPY and string aggregates, just hardcode the
history file contents, this is enough to validate the code.

wal_utils/data/example_success.history

-1	0/09D4F390	no recovery target specified
-2	0/117BEB70	no recovery target specified
-3	0/187BEB38	no recovery target specified
-4	0/188BEB38	no recovery target specified
-5	0/189BEB38	no recovery target specified
-7	0/249BEB38	no recovery target specified

wal_utils/expected/.gitignore

-# Ignore all generated output
-/parse_wal_history.out

wal_utils/output/parse_wal_history.source → wal_utils/expected/parse_wal_history.out

@@ -3,19 +3,18 @@ CREATE EXTENSION wal_utils;
 CREATE TABLE history_data (data text);
 -- Note that COPY truncates newlines.
 -- Load history file that succeeds
-COPY history_data FROM '@abs_srcdir@/data/example_success.history' WITH (FORMAT csv);
-SELECT string_agg(data, E'\n') FROM history_data;
-                      string_agg                      
-------------------------------------------------------
- 1       0/09D4F390      no recovery target specified+
- 2       0/117BEB70      no recovery target specified+
- 3       0/187BEB38      no recovery target specified+
- 4       0/188BEB38      no recovery target specified+
- 5       0/189BEB38      no recovery target specified+
- 7       0/249BEB38      no recovery target specified
-(1 row)
-SELECT parse_wal_history(string_agg(data, E'\n')) FROM history_data;
+INSERT INTO history_data VALUES (
+'# Ignore this comment
+1       0/09D4F390      no recovery target specified
+2       0/117BEB70      no recovery target specified
+3       0/187BEB38      no recovery target specified
+# Other this comment and empty line
+4       0/188BEB38      no recovery target specified
+5       0/189BEB38      no recovery target specified
+7       0/249BEB38      no recovery target specified
+');
+SELECT parse_wal_history(data) FROM history_data;
      parse_wal_history     
 ---------------------------
  (1,,0/9D4F390)

wal_utils/input/parse_wal_history.source

--- Install extension for tests
-CREATE EXTENSION wal_utils;
-
-CREATE TABLE history_data (data text);
-
--- Note that COPY truncates newlines.
--- Load history file that succeeds
-COPY history_data FROM '@abs_srcdir@/data/example_success.history' WITH (FORMAT csv);
-SELECT string_agg(data, E'\n') FROM history_data;
-SELECT parse_wal_history(string_agg(data, E'\n')) FROM history_data;
-DROP TABLE history_data;

wal_utils/sql/.gitignore

-# Ignore all generated input
-/parse_wal_history.sql

wal_utils/sql/parse_wal_history.sql

+-- Install extension for tests
+CREATE EXTENSION wal_utils;
+
+CREATE TABLE history_data (data text);
+
+-- Note that COPY truncates newlines.
+-- Load history file that succeeds
+INSERT INTO history_data VALUES (
+'# Ignore this comment
+1       0/09D4F390      no recovery target specified
+2       0/117BEB70      no recovery target specified
+3       0/187BEB38      no recovery target specified
+# Other this comment and empty line
+
+4       0/188BEB38      no recovery target specified
+5       0/189BEB38      no recovery target specified
+7       0/249BEB38      no recovery target specified
+');
+SELECT parse_wal_history(data) FROM history_data;
+DROP TABLE history_data;