Ensure that binomlogpdf returns non-positive values, t distributions with infinite parameter are supported, and add integration tests (#126)

* Ensure that `binomlogpdf` returns non-positive values

* Add test

* Add integration test

* Bump version

* Handle student t distribution with infinite `ν`

Author: devmotion

.github/workflows/IntegrationTest.yml

@@ -0,0 +1,52 @@
+name: IntegrationTest
+
+on:
+  pull_request:
+    branches:
+      - master
+  push:
+    branches:
+      - master
+    tags: '*'
+
+jobs:
+  test:
+    name: ${{ matrix.package.repo }}/${{ matrix.package.group }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        julia-version: [1]
+        os: [ubuntu-latest]
+        package:
+          - {user: JuliaStats, repo: Distributions.jl}
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: julia-actions/setup-julia@v1
+        with:
+          version: ${{ matrix.julia-version }}
+          arch: x64
+      - uses: julia-actions/julia-buildpkg@latest
+      - name: Clone Downstream
+        uses: actions/checkout@v2
+        with:
+          repository: ${{ matrix.package.user }}/${{ matrix.package.repo }}
+          path: downstream
+      - name: Load this and run the downstream tests
+        shell: julia --color=yes --project=downstream {0}
+        run: |
+          using Pkg
+          try
+            # force it to use this PR's version of the package
+            Pkg.develop(PackageSpec(path="."))  # resolver may fail with main deps
+            Pkg.update()
+            Pkg.test()  # resolver may fail with test time deps
+          catch err
+            err isa Pkg.Resolve.ResolverError || rethrow()
+            # If we can't resolve that means this is incompatible by SemVer and this is fine
+            # It means we marked this as a breaking change, so we don't need to worry about
+            # Mistakenly introducing a breaking change, as we have intentionally made one
+            @info "Not compatible with this release. No problem." exception=err
+            exit(0)  # Exit immediately, as a success
+          end

Project.toml

@@ -1,6 +1,6 @@
 name = "StatsFuns"
 uuid = "4c63d2b9-4356-54db-8cca-17b64c39e42c"
-version = "0.9.11"
+version = "0.9.12"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/distrs/binom.jl

@@ -19,6 +19,6 @@ binompdf(n::Real, p::Real, k::Real) = exp(binomlogpdf(n, p, k))
 binomlogpdf(n::Real, p::Real, k::Real) = binomlogpdf(promote(n, p, k)...)
 function binomlogpdf(n::T, p::T, k::T) where {T<:Real}
     m = clamp(k, 0, n)
-    val = betalogpdf(m + 1, n - m + 1, p) - log(n + 1)
+    val = min(0, betalogpdf(m + 1, n - m + 1, p) - log(n + 1))
     return 0 <= k <= n && isinteger(k) ? val : oftype(val, -Inf)
 end

src/distrs/tdist.jl

@@ -17,6 +17,7 @@ tdistpdf(ν::Real, x::Real) = exp(tdistlogpdf(ν, x))
 
 tdistlogpdf(ν::Real, x::Real) = tdistlogpdf(promote(ν, x)...)
 function tdistlogpdf(ν::T, x::T) where {T<:Real}
+    isinf(ν) && return normlogpdf(x)
     νp12 = (ν + 1) / 2
     return loggamma(νp12) - (logπ + log(ν)) / 2 - loggamma(ν / 2) - νp12 * log1p(x^2 / ν)
 end

test/misc.jl

@@ -63,3 +63,10 @@ end
     @test binomlogpdf(1, 0.5, prevfloat(1.0)) == -Inf
     @test binomlogpdf(1, 0.5, nextfloat(1.0)) == -Inf
 end
+
+@testset "binom special cases" begin
+    for (n, p, k) in ((5, 0.0, 0), (5, 1.0, 5))
+        @test iszero(binomlogpdf(n, p, k))
+        @test isone(binompdf(n, p, k))
+    end
+end

test/rmath.jl

@@ -301,6 +301,8 @@ end
         ((1,), -5f0:0.1f0:5f0),
         ((1,), -Float16(5):Float16(0.1):Float16(5)),
         ((1,), -5//1:5//1),
+        ((Inf,), -5.0:0.1:5.0),
+        ((Inf32,), -5f0:0.1f0:5f0),
     ])
 
     rmathcomp_tests("srdist", [