Add hist unit tests (start with THn).

hist/hist/v7/unit/CMakeLists.txt

+ROOTTEST_ADD_UNITTEST_DIR(Hist)

hist/hist/v7/unit/THn.cxx

+#include "gtest/gtest.h"
+
+#include "THn.h"
+#include "TH1.h"
+#include "TH2.h"
+
+// Filling THn
+TEST(THn, Fill) {
+   Int_t bins[2] = {2, 3};
+   Double_t xmin[2] = {0., -3.};
+   Double_t xmax[2] = {10., 3.};
+   THnD hn("hn", "hn", 2, bins, xmin, xmax);
+
+   {
+      // Non-overflow
+      Double_t x0[2]{4., -0.01};
+      EXPECT_EQ(7, hn.GetBin(x0));
+      EXPECT_DOUBLE_EQ(0.0, hn.GetBinContent(7));
+
+      EXPECT_EQ(7, hn.Fill(x0, 0.42));
+      EXPECT_DOUBLE_EQ(0.42, hn.GetBinContent(7));
+   }
+
+   {
+      Double_t x0[2]{-0.49, -2.90};
+      EXPECT_EQ(1, hn.GetBin(x0));
+      EXPECT_DOUBLE_EQ(0., hn.GetBinContent(10));
+
+      EXPECT_EQ(1, hn.Fill(x0, 0.17));
+      EXPECT_EQ(1, hn.GetBin(x0));
+      EXPECT_DOUBLE_EQ(0.17, hn.GetBinContent(1));
+   }
+
+}
+
+
+TEST(THn, Projection) {
+   Int_t bins[2] = {2, 3};
+   Double_t xmin[2] = {0., -3.};
+   Double_t xmax[2] = {10., 3.};
+   THnD hn("hn", "hn", 2, bins, xmin, xmax);
+
+   {
+      // Non-overflow
+      Double_t x0[2]{4., -0.01};
+      hn.Fill(x0, 0.42);
+   }
+
+   {
+      // Overflow x
+      Double_t x0[2]{-0.49, -2.90};
+      hn.Fill(x0, 0.17);
+   }
+
+   {
+      TH1D* hProj = hn.Projection(0);
+      EXPECT_EQ(2, hProj->GetNbinsX());
+      EXPECT_DOUBLE_EQ(0.17, hProj->GetBinContent(0));
+      EXPECT_DOUBLE_EQ(0.42, hProj->GetBinContent(1));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(2));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(3));
+   }
+
+   {
+      TH1D* hProj = hn.Projection(1);
+      EXPECT_EQ(3, hProj->GetNbinsX());
+      EXPECT_DOUBLE_EQ(0.0, hProj->GetBinContent(0));
+      EXPECT_DOUBLE_EQ(0.17, hProj->GetBinContent(1));
+      EXPECT_DOUBLE_EQ(0.42, hProj->GetBinContent(2));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(3));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(4));
+   }
+
+   {
+      TH2D* hProj = hn.Projection(0, 1);
+      // Yes, x|y are intentionally inverted...
+      EXPECT_EQ(3, hProj->GetNbinsX());
+      EXPECT_EQ(2, hProj->GetNbinsY());
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(0));
+      EXPECT_DOUBLE_EQ(.17, hProj->GetBinContent(1));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(2));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(3));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(4));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(5));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(6));
+      EXPECT_DOUBLE_EQ(.42, hProj->GetBinContent(7));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(8));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(9));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(10));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(11));
+   }
+
+   {
+      // Overflow x and y
+      Double_t x0[2]{-0.49, 3.90};
+      hn.Fill(x0, 43.);
+
+      // With axis range, excluding above point; see ROOT-8457
+      hn.GetAxis(1)->SetRange(1,2);
+      TH1D* hProj = hn.Projection(1);
+      EXPECT_EQ(2, hProj->GetNbinsX());
+      EXPECT_DOUBLE_EQ(0.0, hProj->GetBinContent(0));
+      EXPECT_DOUBLE_EQ(0.17, hProj->GetBinContent(1));
+      EXPECT_DOUBLE_EQ(0.42, hProj->GetBinContent(2));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(3));
+      EXPECT_DOUBLE_EQ(0., hProj->GetBinContent(4));
+   }
+
+
+}