["shell/test", "script"]: make TEST_RUN_NUMBER available

If RUNS_PER_TEST is given, inform each individual test action about
the run number it is executing. This can be used, e.g., to set
random seeds appropriately.

2 files changed, 26 insertions, 2 deletions

diff --git a/rules/shell/test/EXPRESSIONS b/rules/shell/test/EXPRESSIONS
index d1d7e64..ea36b32 100644
--- a/rules/shell/test/EXPRESSIONS
+++ b/rules/shell/test/EXPRESSIONS
@@ -132,7 +132,27 @@
         , {"type": "++", "$1": [["./runner"], {"type": "var", "name": "keep"}]}
         ]
       , [ "test_env"
-        , {"type": "var", "name": "TEST_ENV", "default": {"type": "empty_map"}}
+        , { "type": "map_union"
+          , "$1":
+            [ { "type": "if"
+              , "cond":
+                { "type": "=="
+                , "$1": {"type": "var", "name": "ATTEMPT"}
+                , "$2": null
+                }
+              , "then": {"type": "empty_map"}
+              , "else":
+                { "type": "singelton_map"
+                , "key": "TEST_RUN_NUMBER"
+                , "value": {"type": "var", "name": "ATTEMPT"}
+                }
+              }
+            , { "type": "var"
+              , "name": "TEST_ENV"
+              , "default": {"type": "empty_map"}
+              }
+            ]
+          }
         ]
       ]
     , "body":
diff --git a/rules/shell/test/RULES b/rules/shell/test/RULES
index 98bf27c..19f859f 100644
--- a/rules/shell/test/RULES
+++ b/rules/shell/test/RULES
@@ -12,6 +12,10 @@
       , "TEST_TMPDIR. The test should not assume write permissions"
       , "outside the working directory and the TEST_TMPDIR."
       , "For convenience, the environment variable TMPDIR is also set to TEST_TMPDIR."
+      , ""
+      , "If the configuration variable RUNS_PER_TEST is set, the environment"
+      , "variable TEST_RUN_NUMBER will also be set to the number of the attempt,"
+      , "counting from 0."
       ]
     , "name":
       [ "A name for the test, used in reporting, as well as for staging"
@@ -32,7 +36,7 @@
       [ "The number of times the test should be run in order to detect flakyness."
       , "If set, no test action will be taken from cache."
       ]
-    , "TEST_ENV": ["The environment for executing the test runner."]
+    , "TEST_ENV": ["Additional environment for executing the test runner."]
     }
   , "tainted": ["test"]
   , "artifacts_doc":