Add tests and Github workflow

.github/workflows/main.yml

@@ -0,0 +1,21 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        pg: [16, 15, 14, 13, 12, 11, 10]
+    name: 🐘 PostgreSQL ${{ matrix.pg }}
+    runs-on: ubuntu-latest
+    container: pgxn/pgxn-tools
+    steps:
+      - run: pg-start ${{ matrix.pg }}
+      - uses: actions/checkout@v2
+      - run: pg-build-test

Makefile

@@ -8,4 +8,8 @@ OBJS = $(patsubst %.c,%.o,$(wildcard src/*.c))
 
 PGXS := $(shell $(PG_CONFIG) --pgxs)
 
+TESTS = $(sort $(wildcard test/sql/*.sql))
+REGRESS = $(patsubst test/sql/%.sql,%,$(TESTS))
+REGRESS_OPTS = --inputdir=test --outputdir=test
+
 include $(PGXS)

src/saturated_int.c

@@ -4,6 +4,9 @@
 #include <limits.h>
 
 #include "utils/builtins.h"
+#if PG_VERSION_NUM < 150000
+#include "utils/int8.h"
+#endif
 
 PG_MODULE_MAGIC;
 
@@ -36,7 +39,13 @@ sat_int4_in(PG_FUNCTION_ARGS)
 {
 	char	   *arg = PG_GETARG_CSTRING(0);
 
+#if PG_VERSION_NUM < 150000
+	int64		result;
+	(void) scanint8(arg, false, &result);
+	PG_RETURN_INT32(sat_int8to4_impl(result));
+#else
 	PG_RETURN_INT32(sat_int8to4_impl(pg_strtoint64(arg)));
+#endif
 }
 
 /*

test/expected/001_saturated_int.out

@@ -0,0 +1,7 @@
+create extension saturated_int;
+select 2147483648::saturated_int;
+ saturated_int 
+---------------
+ 2147483647
+(1 row)
+

test/sql/001_saturated_int.sql

@@ -0,0 +1,3 @@
+create extension saturated_int;
+
+select 2147483648::saturated_int;