Add texture base-level related tests

src/tests/gl_tests/FramebufferTest.cpp

@@ -462,6 +462,33 @@ TEST_P(FramebufferTest_ES3, TextureAttachmentMipLevels)
     ExpectFramebufferCompleteOrUnsupported(GL_FRAMEBUFFER);
 }
 
+TEST_P(FramebufferTest_ES3, TextureAttachmentMipLevelsReadBack)
+{
+    // http://anglebug.com/4695
+    ANGLE_SKIP_TEST_IF(IsVulkan());
+
+    GLFramebuffer framebuffer;
+    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
+
+    GLTexture texture;
+    glBindTexture(GL_TEXTURE_2D, texture);
+
+    const std::array<GLColor, 2 * 2> mip0Data = {GLColor::red, GLColor::red, GLColor::red,
+                                                 GLColor::red};
+    const std::array<GLColor, 1 * 1> mip1Data = {GLColor::green};
+
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 4, 4, 0, GL_RGBA, GL_UNSIGNED_BYTE, mip0Data.data());
+    glTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA8, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, mip1Data.data());
+
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 1);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 1);
+    EXPECT_GL_FRAMEBUFFER_COMPLETE(GL_FRAMEBUFFER);
+
+    glClearColor(0, 0, 1.0f, 1.0f);
+    glClear(GL_COLOR_BUFFER_BIT);
+    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::blue);
+}
+
 // Test that passing an attachment COLOR_ATTACHMENTm where m is equal to MAX_COLOR_ATTACHMENTS
 // generates an INVALID_OPERATION.
 // OpenGL ES Version 3.0.5 (November 3, 2016), 4.4.2.4 Attaching Texture Images to a Framebuffer, p.