Make TransformFeedbackTest deterministic.

Instead of using rand(), use a fixed seed RNG. This can ensure runs use the same draw call counts no matter the time of day. Note: there may have been a setting somewhere that was seeding the RNG because I wasn't seeing variation between test runs locally. This change makes it explicit. Bug: angleproject:4029 Change-Id: Ic51bf2a6779da3b96a3357eed99c0f7fa9d81648 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2042210Reviewed-by: Jonah Ryan-Davis <jonahr@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>

Make TransformFeedbackTest deterministic.
3a2522de · Jamie Madill · Commit Bot · 463c318a · 3a2522de
Commit 3a2522de authored Feb 06, 2020 by Jamie Madill Committed by Commit Bot Feb 06, 2020
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TransformFeedbackTest.cpp src/tests/gl_tests/TransformFeedbackTest.cpp +5 -3

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--- a/src/tests/gl_tests/TransformFeedbackTest.cpp
+++ b/src/tests/gl_tests/TransformFeedbackTest.cpp
@@ -555,6 +555,8 @@ TEST_P(TransformFeedbackTest, MultiContext)
        EGL_NONE,
    };
+    // Keep a fixed seed RNG so we are deterministic.
+    RNG rng(0);
    EGLWindow *window = getEGLWindow();
    EGLDisplay display = window->getDisplay();
@@ -572,7 +574,7 @@ TEST_P(TransformFeedbackTest, MultiContext)
    };
    ContextInfo contexts[32];
-    const size_t maxDrawSize = 1024;
+    const size_t maxDrawSize = 512;
    std::vector<float> transformFeedbackData(maxDrawSize);
    for (size_t i = 0; i < maxDrawSize; i++)
@@ -640,9 +642,9 @@ void main(void)
        ASSERT_GL_NO_ERROR();
        // For each pass, draw between 0 and maxDrawSize primitives
-        for (auto &primCount : context.primitiveCounts)
+        for (size_t &primCount : context.primitiveCounts)
        {
-            primCount = rand() % maxDrawSize;
+            primCount = rng.randomIntBetween(1, maxDrawSize);
        }
        glBeginTransformFeedback(GL_POINTS);