introspect: add test dependencies info to test/benchmark JSON

Add the ids of any target that needs to be rebuilt before running the
tests as computed by the backend, to the introspection data for tests and benchmarks.
This also includes anything that appears on the test's command line.

Without this information, IDEs must update the entire build before running
any test.  They can now instead selectively build the test executable
itself and anything that is needed to run it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

7 files changed, 50 insertions, 4 deletions

diff --git a/docs/markdown/IDE-integration.md b/docs/markdown/IDE-integration.md
index 816225f..5188359 100644
--- a/docs/markdown/IDE-integration.md
+++ b/docs/markdown/IDE-integration.md
@@ -247,6 +247,7 @@ line arguments, environment variable settings and how to process the output.
     "is_parallel": true / false,
     "protocol": "exitcode" / "tap",
     "cmd": ["command", "to", "run"],
+    "depends": ["target1-id", "target2-id"],
     "env": {
         "VARIABLE1": "value 1",
         "VARIABLE2": "value 2"
@@ -254,6 +255,11 @@ line arguments, environment variable settings and how to process the output.
 }
 ```
 
+The `depends` entry *(since 0.56.0)* contains target ids; they can be
+looked up in the targets introspection data.  The executable
+pointed to by `cmd` is also included in the entry, as are any
+arguments to the test that are build products.
+
 ## Build system files
 
 It is also possible to get Meson build files used in your current project. This
diff --git a/docs/markdown/snippets/introspect_test_deps.md b/docs/markdown/snippets/introspect_test_deps.md
new file mode 100644
index 0000000..a29ea09
--- /dev/null
+++ b/docs/markdown/snippets/introspect_test_deps.md
@@ -0,0 +1,5 @@
+## Dependencies listed in test and benchmark introspection
+
+The introspection data for tests and benchmarks now includes the target
+ids for executables and built files that are needed by the test.  IDEs can
+use this feature to update the build more quickly before running a test.
diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 7bdccbf..6c5b75a 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -120,7 +120,8 @@ class TestSerialisation:
                  env: build.EnvironmentVariables, should_fail: bool,
                  timeout: T.Optional[int], workdir: T.Optional[str],
                  extra_paths: T.List[str], protocol: TestProtocol, priority: int,
-                 cmd_is_built: bool):
+                 cmd_is_built: bool,
+                 depends: T.List[str]):
         self.name = name
         self.project_name = project
         self.suite = suite
@@ -140,6 +141,7 @@ class TestSerialisation:
         self.priority = priority
         self.needs_exe_wrapper = needs_exe_wrapper
         self.cmd_is_built = cmd_is_built
+        self.depends = depends
 
 
 def get_backend_from_name(backend: str, build: T.Optional[build.Build] = None, interpreter: T.Optional['Interpreter'] = None) -> T.Optional['Backend']:
@@ -830,7 +832,12 @@ class Backend:
                 extra_paths = []
 
             cmd_args = []
+            depends = set(t.depends)
+            if isinstance(exe, build.Target):
+                depends.add(exe)
             for a in unholder(t.cmd_args):
+                if isinstance(a, build.Target):
+                    depends.add(a)
                 if isinstance(a, build.BuildTarget):
                     extra_paths += self.determine_windows_extra_paths(a, [])
                 if isinstance(a, mesonlib.File):
@@ -852,7 +859,8 @@ class Backend:
                                    t.is_parallel, cmd_args, t.env,
                                    t.should_fail, t.timeout, t.workdir,
                                    extra_paths, t.protocol, t.priority,
-                                   isinstance(exe, build.Executable))
+                                   isinstance(exe, build.Executable),
+                                   [x.get_id() for x in depends])
             arr.append(ts)
         return arr
 
diff --git a/mesonbuild/mintro.py b/mesonbuild/mintro.py
index 0049bbd..d55227a 100644
--- a/mesonbuild/mintro.py
+++ b/mesonbuild/mintro.py
@@ -325,6 +325,7 @@ def get_test_list(testdata) -> T.List[T.Dict[str, T.Union[str, int, T.List[str],
         to['is_parallel'] = t.is_parallel
         to['priority'] = t.priority
         to['protocol'] = str(t.protocol)
+        to['depends'] = t.depends
         result.append(to)
     return result
 
diff --git a/run_unittests.py b/run_unittests.py
index 8c03693..2ff2af5 100755
--- a/run_unittests.py
+++ b/run_unittests.py
@@ -4281,6 +4281,7 @@ recommended as it is not supported on some platforms''')
             ('suite', list),
             ('is_parallel', bool),
             ('protocol', str),
+            ('depends', list),
         ]
 
         buildoptions_keylist = [
@@ -4338,12 +4339,28 @@ recommended as it is not supported on some platforms''')
 
         assertKeyTypes(root_keylist, res)
 
+        # Match target ids to input and output files for ease of reference
+        src_to_id = {}
+        out_to_id = {}
+        for i in res['targets']:
+            print(json.dump(i, sys.stdout))
+            out_to_id.update({os.path.relpath(out, self.builddir): i['id']
+                              for out in i['filename']})
+            for group in i['target_sources']:
+                src_to_id.update({os.path.relpath(src, testdir): i['id']
+                                  for src in group['sources']})
+
         # Check Tests and benchmarks
         tests_to_find = ['test case 1', 'test case 2', 'benchmark 1']
+        deps_to_find = {'test case 1': [src_to_id['t1.cpp']],
+                        'test case 2': [src_to_id['t2.cpp'], src_to_id['t3.cpp']],
+                        'benchmark 1': [out_to_id['file2'], src_to_id['t3.cpp']]}
         for i in res['benchmarks'] + res['tests']:
             assertKeyTypes(test_keylist, i)
             if i['name'] in tests_to_find:
                 tests_to_find.remove(i['name'])
+            self.assertEqual(sorted(i['depends']),
+                             sorted(deps_to_find[i['name']]))
         self.assertListEqual(tests_to_find, [])
 
         # Check buildoptions
@@ -4484,6 +4501,7 @@ recommended as it is not supported on some platforms''')
         res_nb = self.introspect_directory(testfile, ['--targets'] + self.meson_args)
 
         # Account for differences in output
+        res_wb = [i for i in res_wb if i['type'] != 'custom']
         for i in res_wb:
             i['filename'] = [os.path.relpath(x, self.builddir) for x in i['filename']]
             if 'install_filename' in i:
diff --git a/test cases/unit/57 introspection/cp.py b/test cases/unit/57 introspection/cp.py
new file mode 100644
index 0000000..cb09cf3
--- /dev/null
+++ b/test cases/unit/57 introspection/cp.py
@@ -0,0 +1,5 @@
+#! /usr/bin/env python3
+
+import sys
+from shutil import copyfile
+copyfile(*sys.argv[1:])
diff --git a/test cases/unit/57 introspection/meson.build b/test cases/unit/57 introspection/meson.build
index 5d4dd02..3a3db10 100644
--- a/test cases/unit/57 introspection/meson.build
+++ b/test cases/unit/57 introspection/meson.build
@@ -26,6 +26,9 @@ var1 = '1'
 var2 = 2.to_string()
 var3 = 'test3'
 
+cus = custom_target('custom target test', output: 'file2', input: 'cp.py',
+                    command: [find_program('cp.py'), '@INPUT@', '@OUTPUT@'])
+
 t1 = executable('test' + var1, ['t1.cpp'], link_with: [sharedlib], install: not false, build_by_default: get_option('test_opt2'))
 t2 = executable('test@0@'.format('@0@'.format(var2)), sources: ['t2.cpp'], link_with: [staticlib])
 t3 = executable(var3, 't3.cpp', link_with: [sharedlib, staticlib], dependencies: [dep1])
@@ -44,8 +47,8 @@ osmesa_lib_name = osmesa_lib_name + osmesa_bits
 message(osmesa_lib_name) # Infinite recursion gets triggered here when the parameter osmesa_lib_name is resolved
 
 test('test case 1', t1)
-test('test case 2', t2)
-benchmark('benchmark 1', t3)
+test('test case 2', t2, depends: t3)
+benchmark('benchmark 1', t3, args: cus)
 
 ### Stuff to test the AST JSON printer
 foreach x : ['a', 'b', 'c']