Add is_indexed() to upgrade script.

And record it in Changes.

Changes

@@ -5,7 +5,9 @@ Revision history for pgTAP
 ---------------------------
 * Fixed the default description for `hasnt_opclass()` to say "should not
   exist" instead of "should exist", thanks to Rodolphe Quiédeville (PR #99).
-
+* Added `is_indexed()`, which test to see that specific table columns are
+  indexed, thanks to Rodolphe Quiédeville (PR #103).
+
 0.96.0 2016-05-16T20:53:57Z
 ---------------------------
 * Added an optional `:exclude_pattern` parameter to `findfuncs()` to prevent

sql/pgtap--0.96.0--0.97.0.sql

@@ -1 +1,93 @@
--- No changes yet.
+CREATE OR REPLACE FUNCTION _is_indexed( NAME, NAME, NAME[])
+RETURNS BOOLEAN AS $$
+    WITH cols AS (
+       SELECT x.indexrelid, x.indrelid, unnest(x.indkey) as colid
+         FROM pg_catalog.pg_index x
+         JOIN pg_catalog.pg_class r ON r.oid = x.indrelid
+         JOIN pg_catalog.pg_namespace n ON n.oid = r.relnamespace
+       WHERE n.nspname = $1
+         AND r.relname = $2),
+    colsdef AS (
+       SELECT cols.indexrelid, cols.indrelid, array_agg(a.attname) as cols
+         FROM cols
+         JOIN pg_catalog.pg_attribute a ON (a.attrelid = cols.indrelid
+                                            AND a.attnum = cols.colid)
+       GROUP BY 1, 2)
+    SELECT EXISTS (
+    SELECT TRUE
+      FROM colsdef
+    WHERE colsdef.cols::NAME[] = $3
+    );
+$$ LANGUAGE sql;
+
+CREATE OR REPLACE FUNCTION _is_indexed( NAME, NAME[])
+RETURNS BOOLEAN AS $$
+    WITH cols AS (
+       SELECT x.indexrelid, x.indrelid, unnest(x.indkey) as colid
+         FROM pg_catalog.pg_index x
+         JOIN pg_catalog.pg_class r ON r.oid = x.indrelid
+       WHERE r.relname = $1),
+    colsdef AS (
+       SELECT cols.indexrelid, cols.indrelid, array_agg(a.attname) as cols
+         FROM cols
+         JOIN pg_catalog.pg_attribute a ON (a.attrelid = cols.indrelid
+                                            AND a.attnum = cols.colid)
+       GROUP BY 1, 2)
+    SELECT EXISTS (
+    SELECT TRUE
+      FROM colsdef
+    WHERE colsdef.cols::NAME[] = $2
+    );
+$$ LANGUAGE sql;
+
+-- is_indexed( schema, table, columns[], description )
+CREATE OR REPLACE FUNCTION is_indexed ( NAME, NAME, NAME[], TEXT )
+RETURNS TEXT AS $$
+   SELECT ok ( _is_indexed( $1, $2, $3), $4);
+$$ LANGUAGE sql;
+
+-- is_indexed( schema, table, columns[] )
+CREATE OR REPLACE FUNCTION is_indexed ( NAME, NAME, NAME[] )
+RETURNS TEXT AS $$
+   SELECT ok ( _is_indexed( $1, $2, $3), 'An index on ' || quote_ident($1) || '.' || quote_ident($2) || ' with ' || $3::text || ' should exist');
+$$ LANGUAGE sql;
+
+-- is_indexed( table, columns[], description )
+CREATE OR REPLACE FUNCTION is_indexed ( NAME, NAME[], TEXT )
+RETURNS TEXT AS $$
+   SELECT ok ( _is_indexed( $1, $2), $3);
+$$ LANGUAGE sql;
+
+-- is_indexed( table, columns[] )
+CREATE OR REPLACE FUNCTION is_indexed ( NAME, NAME[] )
+RETURNS TEXT AS $$
+   SELECT ok ( _is_indexed( $1, $2), 'An index on ' || quote_ident($1) || ' with ' || $2::text || ' should exist');
+$$ LANGUAGE sql;
+
+-- is_indexed( schema, table, column, description )
+CREATE OR REPLACE FUNCTION is_indexed ( NAME, NAME, NAME, TEXT )
+RETURNS TEXT AS $$
+   SELECT ok ( _is_indexed( $1, $2, ARRAY[$3]::NAME[]), $4);
+$$ LANGUAGE sql;
+
+-- is_indexed( schema, table, column )
+CREATE OR REPLACE FUNCTION is_indexed ( NAME, NAME, NAME )
+RETURNS TEXT AS $$
+    SELECT CASE WHEN _is_schema( $1 ) THEN
+        -- Looking for schema.table index.
+            ok ( _is_indexed( $1, $2, ARRAY[$3]::NAME[]),
+                'An index on ' || quote_ident($1) || '.' || quote_ident($2)
+                    || ' on column ' || quote_ident($3) || ' should exist')
+        ELSE
+        -- Looking for particular columns.
+            ok ( _is_indexed( $1, ARRAY[$2]::NAME[]), $3)
+        END;
+$$ LANGUAGE sql;
+
+-- is_indexed( table, column )
+CREATE OR REPLACE FUNCTION is_indexed ( NAME, NAME )
+RETURNS TEXT AS $$
+   SELECT ok ( _is_indexed( $1, ARRAY[$2]::NAME[]),
+              'An index on ' || quote_ident($1) || ' on column '
+                  || $2::text || ' should exist');
+$$ LANGUAGE sql;