postgis sql interface test

Author: olirice

flake.nix

@@ -421,7 +421,7 @@
 
             #pg_prove -p 5432 -h localhost -d testing ${sqlTests}/*.sql
 
-			      mkdir -p $out/regression_output
+			mkdir -p $out/regression_output
             pg_regress \
               --use-existing \
               --dbname=testing \

nix/docs/adding-tests.md

@@ -1,12 +1,46 @@
 There are basically two types of tests you can add:
 
 - pgTAP based tests, and
+- pg\_regress tests
 - Migration tests.
 
-In both cases, a number of extensions may be installed into the database for
+In all cases, a number of extensions may be installed into the database for
 use; you can see those in both [postgresql.conf.in](../tests/postgresql.conf.in)
 and [prime.sql](../tests/prime.sql) (extensions may be enabled in either place.)
 
+## pg\_regress tests
+
+pg\_regress tests are in [tests/sql](./../tests/sql/) with output in [tests/expected](./../tests/expected/).
+To create a new test, create a new SQL file in [tests/sql](./../tests/sql/) and then run:
+
+```
+nix flake check -L
+```
+
+Next, review the logs to identify where the test output was written
+
+```
+postgres> CREATE EXTENSION IF NOT EXISTS index_advisor;
+postgres> CREATE EXTENSION  
+postgres> (using postmaster on localhost, port 5432)    
+postgres> ============== running regression test queries        ==============
+postgres> test new_test                     ... diff: /nix/store/5gk419ddz7mzzwhc9j6yj5i8lkw67pdl-tests/expected/new_test.out: No such file or directory
+postgres> diff command failed with status 512: diff  "/nix/store/5gk419ddz7mzzwhc9j6yj5i8lkw67pdl-tests/expected/new_test.out" "/nix/store/2fbrvnnr7iz6yigyf0rb0vxnyqvrgxzp-postgres-15.6-check-harness/regression_output/results/new_test.out" > "/nix/store/2fbrvnnr7iz6yigyf0rb0vxnyqvrgxzp-postgres-15.6-check-harness/regression_output/results/new_test.out.diff
+```
+
+and copy the `regression_output` directory to where you can review
+
+```
+cp -r /nix/store/2fbrvnnr7iz6yigyf0rb0vxnyqvrgxzp-postgres-15.6-check-harness/regression_output .
+```
+
+Then you can review the contents of `regression_output/results/new_test.out` to see if it matches what you expected.
+
+If it does match your expectations, copy the file to [tests/expected](./../tests/expected/) and the test will pass on the next run.
+
+If the output does not match your expectations, update the `<new_test>.sql` file, re-run with `nix flake check -L` and try again
+
+
 ## pgTAP tests
 
 These are super easy: simply add `.sql` files to the