test: Add unit tests for epoxy_gl_version() and epoxy_glsl_version().

Based on a bug report I got on IRC.

v2: Drop glx includes, add to automake.

test/Makefile.am

@@ -57,6 +57,7 @@ TESTS = \
 	$(GLX_TESTS) \
 	$(EGL_AND_GLX_TESTS) \
 	$(WGL_TESTS) \
+	gl_version$(EXEEXT) \
 	headerguards$(EXEEXT) \
 	miscdefines$(EXEEXT) \
 	khronos_typedefs$(EXEEXT) \

test/gl_version.c

@@ -0,0 +1,89 @@
+/*
+ * Copyright © 2018 Broadcom
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <assert.h>
+#include "epoxy/gl.h"
+
+GLenum mock_enum;
+const char *mock_gl_version;
+const char *mock_glsl_version;
+
+static const GLubyte *override_glGetString(GLenum name)
+{
+    switch (name) {
+    case GL_VERSION:
+        return (GLubyte *)mock_gl_version;
+    case GL_SHADING_LANGUAGE_VERSION:
+        return (GLubyte *)mock_glsl_version;
+    default:
+        assert(!"unexpected glGetString() enum");
+        return 0;
+    }
+}
+
+static bool
+test_version(const char *gl_string, int gl_version,
+             const char *glsl_string, int glsl_version)
+{
+    int epoxy_version;
+
+    mock_gl_version = gl_string;
+    mock_glsl_version = glsl_string;
+
+    epoxy_version = epoxy_gl_version();
+    if (epoxy_version != gl_version) {
+        fprintf(stderr,
+                "glGetString(GL_VERSION) = \"%s\" returned epoxy_gl_version() "
+                "%d instead of %d\n", gl_string, epoxy_version, gl_version);
+        return false;
+    }
+
+
+    epoxy_version = epoxy_glsl_version();
+    if (epoxy_version != glsl_version) {
+        fprintf(stderr,
+                "glGetString() = \"%s\" returned epoxy_glsl_version() "
+                "%d instead of %d\n", glsl_string, epoxy_version, glsl_version);
+        return false;
+    }
+
+    return true;
+}
+
+int
+main(int argc, char **argv)
+{
+    bool pass = true;
+
+    epoxy_glGetString = override_glGetString;
+
+    pass = pass && test_version("3.0 Mesa 13.0.6", 30,
+                                "1.30", 130);
+    pass = pass && test_version("OpenGL ES 3.2 Mesa 18.3.0-devel", 32,
+                                "OpenGL ES GLSL ES 3.20", 320);
+    pass = pass && test_version("4.5.0 NVIDIA 384.130", 45,
+                                "4.50", 450);
+
+    return pass != true;
+}

test/meson.build

@@ -33,6 +33,12 @@ test('khronos_typedefs',
                 c_args: common_cflags,
                 dependencies: libepoxy_dep,
                 include_directories: libepoxy_inc))
+test('gl_version',
+     executable('gl_version',
+                'gl_version.c',
+                c_args: common_cflags,
+                dependencies: libepoxy_dep,
+                include_directories: libepoxy_inc))
 
 if build_egl and build_x11_tests
   egl_common_sources = [ 'egl_common.h', 'egl_common.c', ]