Add runner for GDScript testing

This is meant for testing the GDScript implementation, not for testing
user scripts nor testing the engine using scripts.

Tests consists in a GDScript file and a .out file with the expected
output. The .out file format is: expected status (based on the enum
GDScriptTest::TestStatus) on the first line, followed by either an error
message or the resulting output. Warnings are added after the first
line, before the output (or compiler errors) if the parser pass without
any error.

The test script must have a function called `test()` which takes no
argument. Such function will be called by the test runner. The test
should not have any dependency unless it's part of the test too. Global
classes (using `class_name`) are registered before the runner starts, so
those should work if needed.

Use the command `godot --gdscript-generate-tests
godot-source/modules/gdscript/tests/scripts` to update the .out files
with the current output (make sure the output are the expected values
before committing).

The tests themselves are part of the doctest suite so those can be
executed with `godot --test`.

Co-authored-by: Andrii Doroshenko (Xrayez) <xrayez@gmail.com>

modules/gdscript/tests/scripts/.gitignore

@@ -0,0 +1,2 @@
+# Ignore metadata if someone open this on Godot.
+/.godot

modules/gdscript/tests/scripts/parser-errors/missing-argument.gd

@@ -0,0 +1,6 @@
+func args(a, b):
+    print(a)
+    print(b)
+
+func test():
+    args(1,)

modules/gdscript/tests/scripts/parser-errors/missing-argument.out

@@ -0,0 +1,2 @@
+GDTEST_ANALYZER_ERROR
+Too few arguments for "args()" call. Expected at least 2 but received 1.

modules/gdscript/tests/scripts/parser-errors/missing-closing-expr-paren.gd

@@ -0,0 +1,2 @@
+func test():
+    var a = ("missing paren ->"

modules/gdscript/tests/scripts/parser-errors/missing-closing-expr-paren.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected closing ")" after grouping expression.

modules/gdscript/tests/scripts/parser-errors/missing-colon.gd

@@ -0,0 +1,3 @@
+func test():
+    if true # Missing colon here.
+        print("true")

modules/gdscript/tests/scripts/parser-errors/missing-colon.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected ":" after "if" condition.

modules/gdscript/tests/scripts/parser-errors/missing-paren-after-args.gd

@@ -0,0 +1,6 @@
+func args(a, b):
+    print(a)
+    print(b)
+
+func test():
+    args(1,2

modules/gdscript/tests/scripts/parser-errors/missing-paren-after-args.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected closing ")" after call arguments.

modules/gdscript/tests/scripts/parser-errors/mixing-tabs-spaces.gd

@@ -0,0 +1,3 @@
+func test():
+    print("Using spaces")
+	print("Using tabs")

modules/gdscript/tests/scripts/parser-errors/mixing-tabs-spaces.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Used "\t" for indentation instead " " as used before in the file.

modules/gdscript/tests/scripts/parser-errors/nothing-after-dollar.gd

@@ -0,0 +1,3 @@
+extends Node
+func test():
+    var a = $ # Expected some node path.

modules/gdscript/tests/scripts/parser-errors/nothing-after-dollar.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expect node path as string or identifier after "$".

modules/gdscript/tests/scripts/parser-errors/wrong-value-after-dollar-slash.gd

@@ -0,0 +1,3 @@
+extends Node
+func test():
+    $MyNode/23 # Can't use number here.

modules/gdscript/tests/scripts/parser-errors/wrong-value-after-dollar-slash.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expect node path after "/".

modules/gdscript/tests/scripts/parser-errors/wrong-value-after-dollar.gd

@@ -0,0 +1,3 @@
+extends Node
+func test():
+    $23 # Can't use number here.

modules/gdscript/tests/scripts/parser-errors/wrong-value-after-dollar.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expect node path as string or identifier after "$".

modules/gdscript/tests/scripts/parser-features/semicolon-as-end-statement.gd

@@ -0,0 +1,2 @@
+func test():
+    print("A"); print("B")

modules/gdscript/tests/scripts/parser-features/semicolon-as-end-statement.out

@@ -0,0 +1,3 @@
+GDTEST_OK
+A
+B

modules/gdscript/tests/scripts/parser-features/trailing-comma-in-function-args.gd

@@ -0,0 +1,7 @@
+# See https://github.com/godotengine/godot/issues/41066.
+
+func f(p, ): ## <-- no errors
+	print(p)
+
+func test():
+	f(0, ) ## <-- no error

modules/gdscript/tests/scripts/parser-features/trailing-comma-in-function-args.out

@@ -0,0 +1,2 @@
+GDTEST_OK
+0

modules/gdscript/tests/scripts/parser-features/variable-declaration.gd

@@ -0,0 +1,12 @@
+var a # No init.
+var b = 42 # Init.
+
+func test():
+	var c # No init, local.
+	var d = 23 # Init, local.
+
+	a = 1
+	c = 2
+
+	prints(a, b, c, d)
+	print("OK")

modules/gdscript/tests/scripts/parser-features/variable-declaration.out

@@ -0,0 +1,7 @@
+GDTEST_OK
+>> WARNING
+>> Line: 5
+>> UNASSIGNED_VARIABLE
+>> The variable 'c' was used but never assigned a value.
+1 42 2 23
+OK

modules/gdscript/tests/scripts/parser-warnings/unused-variable.gd

@@ -0,0 +1,2 @@
+func test():
+    var unused = "not used"

modules/gdscript/tests/scripts/parser-warnings/unused-variable.out

@@ -0,0 +1,5 @@
+GDTEST_OK
+>> WARNING
+>> Line: 2
+>> UNUSED_VARIABLE
+>> The local variable 'unused' is declared but never used in the block. If this is intended, prefix it with an underscore: '_unused'

modules/gdscript/tests/scripts/project.godot

@@ -0,0 +1,10 @@
+; This is not an actual project.
+; This config only exists to properly set up the test environment.
+; It also helps for opening Godot to edit the scripts, but please don't
+; let the editor changes be saved.
+
+config_version=4
+
+[application]
+
+config/name="GDScript Integration Test Suite"