add build failure example with ctest (#29)

Change-Id: I49f2a9991686715dda2e529b19206909ec1a7c79

README.md

@@ -57,10 +57,43 @@ When running tests, `skytest` will attempt to invoke test closures at
 compile-time. If able to, results will be classified `CONSTEXPR PASS` or
 `CONSTEXPR FAIL` instead of `PASS` or `FAIL`.
 
+<details><summary>requiring compile-time evaluation of tests</summary>
+
+
 The `ctest` literal can be used to require closures to be tested at
 compile-time. In order to be usable with `ctest`, test closures must be empty
 and non-constexpr functions must not be invoked.
 
+```cpp:example/ctest_fail.cpp
+#include "skytest/skytest.hpp"
+
+auto main() -> int
+{
+  using namespace skytest::literals;
+  using ::skytest::expect;
+  using ::skytest::lt;
+
+  static auto n = 0;
+  "read non-const"_ctest = [] { return expect(lt(0, n)); };
+}
+
+```
+
+results in the follow build error (snippet):
+
+```console:example/ctest_fail.log
+external/skytest/src/detail/test_style.hpp:43:27: error: the value of 'n' is not usable in a constant expression
+   43 |     static constexpr auto value = std::optional<bool>{bool{F{}()}};
+      |                           ^~~~~
+ctest_fail.cpp:9:15: note: 'int n' is not const
+    9 |   static auto n = 0;
+      |               ^
+
+```
+
+</details>
+
+
 ## examples
 
 #### binary comparisons

example/BUILD.bazel

@@ -1,4 +1,5 @@
 load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library", "cc_test")
+load("//rules:sh_binary_template.bzl", "sh_binary_template")
 load("//rules:binary_log.bzl", "synchronized_binary_log")
 
 cc_library(
@@ -30,6 +31,17 @@ synchronized_binary_log(
     src = ":minimal_fail",
 )
 
+sh_binary_template(
+    name = "ctest_fail",
+    srcs = ["ctest_fail.sh.tmpl"],
+    data = ["ctest_fail.cpp"],
+)
+
+synchronized_binary_log(
+    name = "ctest_fail_log",
+    src = ":ctest_fail",
+)
+
 cc_test(
     name = "binary_comparisons",
     srcs = ["binary_comparisons.cpp"],

example/ctest_fail.cpp

@@ -0,0 +1,11 @@
+#include "skytest/skytest.hpp"
+
+auto main() -> int
+{
+  using namespace skytest::literals;
+  using ::skytest::expect;
+  using ::skytest::lt;
+
+  static auto n = 0;
+  "read non-const"_ctest = [] { return expect(lt(0, n)); };
+}

example/ctest_fail.log

@@ -0,0 +1,6 @@
+external/skytest/src/detail/test_style.hpp:43:27: error: the value of 'n' is not usable in a constant expression
+   43 |     static constexpr auto value = std::optional<bool>{bool{F{}()}};
+      |                           ^~~~~
+ctest_fail.cpp:9:15: note: 'int n' is not const
+    9 |   static auto n = 0;
+      |               ^

example/ctest_fail.sh.tmpl

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+source $(find -L . -path \*/rules/prelude.sh -print -quit)
+prelude "${BASH_SOURCE[0]}"
+
+cp $(find -L . -path \*/example/ctest_fail.cpp -print -quit) .
+
+cat >>BUILD.bazel <<EOF
+cc_binary(
+    name = "ctest_fail",
+    srcs = ["ctest_fail.cpp"],
+    copts = [
+        "-Werror",
+        "-Wall",
+        "-Wextra",
+    ],
+    deps = [":external_skytest"],
+)
+EOF
+
+startup_opts=(
+    --output_user_root=/tmp/bazel
+    --output_base=/tmp/bazel/output
+)
+build_opts=(
+    --symlink_prefix=/
+    --noshow_progress
+    --ui_event_filters=-info,-stdout
+    --color=no
+)
+
+start="error: the value of 'n' is not usable in a constant expression"
+stop="Target .*:ctest_fail failed to build"
+
+bazel \
+    ${startup_opts[@]} \
+    build \
+    ${build_opts[@]} \
+    //:ctest_fail 2>&1 \
+    | sed -n "/$start/,/$stop/ p" `# only print from start to stop` \
+    | sed '$d'                     # remove the stop line
+

rules/BUILD.bazel

@@ -1,4 +1,36 @@
+load("@bazel_skylib//rules:expand_template.bzl", "expand_template")
+load(
+    "@local_config_info//:defs.bzl",
+    "BAZEL_BIN",
+    "BAZEL_EXTERNAL_DIR",
+    "BAZEL_WORKSPACE_ROOT",
+    "XDG_CACHE_HOME",
+)
+
 exports_files(
     ["skytest_test.sh"],
     visibility = ["//test:__pkg__"],
 )
+
+expand_template(
+    name = "gen_prelude_sh",
+    out = "prelude.sh",
+    substitutions = {
+        "$BAZEL_BIN": BAZEL_BIN,
+        "$BAZEL_EXTERNAL_DIR": BAZEL_EXTERNAL_DIR,
+        "$BAZEL_WORKSPACE_ROOT": BAZEL_WORKSPACE_ROOT,
+        "$XDG_CACHE_HOME": XDG_CACHE_HOME,
+    },
+    tags = ["manual"],
+    template = "prelude.sh.tmpl",
+    visibility = ["//visibility:private"],
+)
+
+sh_library(
+    name = "prelude_sh",
+    srcs = ["prelude.sh"],
+    visibility = [
+        "//example:__pkg__",
+        "//test:__pkg__",
+    ],
+)

rules/binary_log.bzl

@@ -22,9 +22,9 @@ def binary_log(
     """
     native.genrule(
         name = name,
-        srcs = [src],
+        tools = [src],
         outs = [log],
-        cmd = "$(execpath {}) > $@ || true".format(src),
+        cmd = "$(execpath {}) &> $@ || true".format(src),
         testonly = True,
         tags = ["manual"],
         visibility = ["//visibility:private"],
@@ -64,17 +64,14 @@ def synchronized_binary_log(
 
     native.genrule(
         name = name + "_update_sh",
-        srcs = [
-            src,
-            log,
-        ],
+        srcs = [log],
+        tools = [src],
         outs = [name + ".update.sh"],
         cmd = """
 set -euo pipefail
 echo "set -euo pipefail" > $@
 echo "" >> $@
-echo "cd {workspace_dir}" >> $@
-echo "$(execpath {src}) > $(rootpath {log}) || true" >> $@
+echo "{workspace_dir}/$(execpath {src}) &> {workspace_dir}/$(rootpath {log}) || true" >> $@
 """.format(
             src = src,
             log = log,
@@ -96,4 +93,5 @@ echo "$(execpath {src}) > $(rootpath {log}) || true" >> $@
     native.sh_binary(
         name = name + ".update",
         srcs = [name + ".update.sh"],
+        data = [src],
     )

test/prelude.sh.tmpl → rules/prelude.sh.tmpl

@@ -4,8 +4,11 @@ set -euo pipefail
 function prelude() {
 
 TEST_PATH="$(readlink -f $1)"
-SCRIPT_NAME="${TEST_PATH##*/test/}}"
-WORKSPACE="${SCRIPT_NAME%.*}"
+
+PRUNE_TEST="${TEST_PATH##*/test/}}"
+PRUNE_EXAMPLE="${PRUNE_TEST##*/example/}}"
+
+WORKSPACE="${PRUNE_EXAMPLE%.*}"
 
 cat >> .bazelrc <<EOF
 startup --max_idle_secs=1

rules/sh_binary_template.bzl

@@ -6,11 +6,11 @@ load("@bazel_skylib//rules:expand_template.bzl", "expand_template")
 
 def sh_binary_template(
         name,
-        substitutions,
+        substitutions = {},
         template = None,
         out = None,
         srcs = [],
-        deps = []):
+        **kwargs):
     """
     Combines expand_template with sh_binary
 
@@ -25,8 +25,8 @@ def sh_binary_template(
         Key-value mappings.
       srcs: string_label_list
         `srcs` used for `sh_binary`
-      deps: string_label_list
-        `deps` used for `sh_binary`
+      **kwargs: dict
+        additional args passed to `sh_binary`
     """
     if len(srcs) == 1 and template == None:
         template = srcs[0]
@@ -45,8 +45,11 @@ def sh_binary_template(
 
     binary_src = lambda src: src if src != template else out
 
+    data = kwargs.pop("data", [])
+
     native.sh_binary(
         name = name,
         srcs = [binary_src(src) for src in srcs],
-        deps = deps,
+        data = data + ["//rules:prelude_sh"],
+        **kwargs
     )

rules/skytest_test.bzl

@@ -104,7 +104,6 @@ echo "done" >> $@
                     "$CC_BINARY_CXXSTD": std,
                     "$CC_BINARY_MALLOC": malloc,
                 },
-                "deps": ["//test:prelude_sh"],
             }
         else:
             fail("unhandled binary_type: {}".format(binary_type))

scripts/README.md.tmpl

@@ -29,10 +29,23 @@ When running tests, `skytest` will attempt to invoke test closures at
 compile-time. If able to, results will be classified `CONSTEXPR PASS` or
 `CONSTEXPR FAIL` instead of `PASS` or `FAIL`.
 
+<details><summary>requiring compile-time evaluation of tests</summary>
+
+
 The `ctest` literal can be used to require closures to be tested at
 compile-time. In order to be usable with `ctest`, test closures must be empty
 and non-constexpr functions must not be invoked.
 
+```cpp:example/ctest_fail.cpp
+```
+
+results in the follow build error (snippet):
+
+```console:example/ctest_fail.log
+```
+
+</details>
+
 ## examples
 
 #### binary comparisons

test/BUILD.bazel

@@ -1,34 +1,6 @@
 load("//rules:skytest_test.bzl", "skytest_test")
 load("//rules:sh_binary_template.bzl", "sh_binary_template")
 load("@rules_cc//cc:defs.bzl", "cc_library")
-load("@bazel_skylib//rules:expand_template.bzl", "expand_template")
-load(
-    "@local_config_info//:defs.bzl",
-    "BAZEL_BIN",
-    "BAZEL_EXTERNAL_DIR",
-    "BAZEL_WORKSPACE_ROOT",
-    "XDG_CACHE_HOME",
-)
-
-expand_template(
-    name = "gen_prelude_sh",
-    testonly = True,
-    out = "prelude.sh",
-    substitutions = {
-        "$BAZEL_BIN": BAZEL_BIN,
-        "$BAZEL_EXTERNAL_DIR": BAZEL_EXTERNAL_DIR,
-        "$BAZEL_WORKSPACE_ROOT": BAZEL_WORKSPACE_ROOT,
-        "$XDG_CACHE_HOME": XDG_CACHE_HOME,
-    },
-    tags = ["manual"],
-    template = "prelude.sh.tmpl",
-    visibility = ["//visibility:private"],
-)
-
-sh_library(
-    name = "prelude_sh",
-    srcs = ["prelude.sh"],
-)
 
 skytest_test(
     name = "pass_test",

test/ctest_build_failure.sh.tmpl

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-source test/prelude.sh
+source rules/prelude.sh
 prelude "${BASH_SOURCE[0]}"
 
 cat >>BUILD.bazel <<EOF
@@ -40,4 +40,4 @@ auto main() -> int
 }
 EOF
 
-bazel build -s //:ctest_build_failure
+bazel build -s //:ctest_build_failure

test/noreturn_expect.sh.tmpl

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-source test/prelude.sh
+source rules/prelude.sh
 prelude "${BASH_SOURCE[0]}"
 
 cat >>BUILD.bazel <<EOF